diff --git a/CMakeLists.txt b/CMakeLists.txt
index ea09cec..0d6781c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -84,5 +84,5 @@ configure_file(
 
 # 添加库源文件地址
 add_subdirectory(lib)
-add_subdirectory(tool)
 add_subdirectory(example)
+add_subdirectory(tool)
\ No newline at end of file
diff --git a/lib/potential/gkernel_sphere.h b/lib/potential/gkernel_sphere.h
index 57495d0..6f50be6 100644
--- a/lib/potential/gkernel_sphere.h
+++ b/lib/potential/gkernel_sphere.h
@@ -31,9 +31,15 @@
 #include "gctl/core/array.h"
 #include "gctl/geometry/point3c.h"
 #include "gctl/geometry/sphere.h"
+#include "gctl/optimization/loss_func.h"
 
 #include "gm_data.h"
 
+#ifdef GCTL_POTENTIAL_AUTODIFF
+#include "autodiff/reverse/var.hpp"
+#include "autodiff/reverse/var/eigen.hpp"
+#endif // GCTL_POTENTIAL_AUTODIFF
+
 namespace gctl
 {
     /**
@@ -60,6 +66,24 @@ namespace gctl
 	 */
 	void gobser_sphere(array<double> &out_obs, const array<point3dc> &obsp, const sphere &gs, 
 		gravitational_field_type_e comp_id = Vz, value_operator_e valtype = ReplaceVal);
+
+#ifdef GCTL_POTENTIAL_AUTODIFF
+	
+	/**
+	 * @brief 计算球体的正演重力异常与观测数据的数据拟合差，以及其相对于球体质量与埋深的偏导数
+	 * 
+	 * @param depth_der 相对于埋深的偏导数
+	 * @param mass_der 相对于质量的偏导数
+	 * @param mass_loc 球体的位置
+	 * @param mass 球体的质量
+	 * @param lf 数据拟合差对象（包含了观测数据与不确定度等信息）
+	 * @param obsp 观测点位
+	 */
+	void gobser_wrt_mass_depth(double &depth_der, double &mass_der, const point3dc &mass_loc, 
+		double mass, loss_func &lf, const array<point3dc> &obsp);
+
+#endif // GCTL_POTENTIAL_AUTODIFF
+
 }
 
 #endif // _GCTL_GRAV_KERNEL_SPHERE_H
\ No newline at end of file
diff --git a/lib/potential/gkernel_sphere_mass_depth.cpp b/lib/potential/gkernel_sphere_mass_depth.cpp
new file mode 100644
index 0000000..8b6dc92
--- /dev/null
+++ b/lib/potential/gkernel_sphere_mass_depth.cpp
@@ -0,0 +1,83 @@
+/********************************************************
+ *  ██████╗  ██████╗████████╗██╗
+ * ██╔════╝ ██╔════╝╚══██╔══╝██║
+ * ██║  ███╗██║        ██║   ██║
+ * ██║   ██║██║        ██║   ██║
+ * ╚██████╔╝╚██████╗   ██║   ███████╗
+ *  ╚═════╝  ╚═════╝   ╚═╝   ╚══════╝
+ * Geophysical Computational Tools & Library (GCTL)
+ *
+ * Copyright (c) 2022  Yi Zhang (yizhang-geo@zju.edu.cn)
+ *
+ * GCTL is distributed under a dual licensing scheme. You can redistribute 
+ * it and/or modify it under the terms of the GNU Lesser General Public 
+ * License as published by the Free Software Foundation, either version 2 
+ * of the License, or (at your option) any later version. You should have 
+ * received a copy of the GNU Lesser General Public License along with this 
+ * program. If not, see <http://www.gnu.org/licenses/>.
+ * 
+ * If the terms and conditions of the LGPL v.2. would prevent you from using 
+ * the GCTL, please consider the option to obtain a commercial license for a 
+ * fee. These licenses are offered by the GCTL's original author. As a rule, 
+ * licenses are provided "as-is", unlimited in time for a one time fee. Please 
+ * send corresponding requests to: yizhang-geo@zju.edu.cn. Please do not forget 
+ * to include some description of your company and the realm of its activities. 
+ * Also add information on how to contact you by electronic and paper mail.
+ ******************************************************/
+
+#include "gkernel_sphere.h"
+
+#ifdef GCTL_POTENTIAL_AUTODIFF
+
+autodiff::var gobser_mass_depth_vz_sig(const gctl::point3dc &obsp, double loc_x, 
+    double loc_y, const autodiff::ArrayXvar& depth_mass);
+
+void gctl::gobser_wrt_mass_depth(double &depth_der, double &mass_der, const point3dc &mass_loc, 
+    double mass, loss_func &lf, const array<point3dc> &obsp)
+{
+    double tmp_val, tmp_grad;
+    autodiff::var tmp_obs;
+    autodiff::ArrayXvar depth_mass;
+    Eigen::VectorXd ders;
+
+    depth_der = 0.0;
+    mass_der = 0.0;
+
+    int i;
+    int o_size = obsp.size();
+
+#pragma omp parallel for private (i, tmp_val, tmp_grad, tmp_obs, depth_mass, ders) schedule(guided)
+    for (i = 0; i < o_size; i++)
+    {
+        depth_mass.resize(2);
+        depth_mass[0] = mass_loc.z;
+        depth_mass[1] = mass;
+
+        ders.setZero();
+        tmp_obs = gobser_mass_depth_vz_sig(obsp[i], mass_loc.x, mass_loc.y, depth_mass);
+        ders = autodiff::gradient(tmp_obs, depth_mass);
+        tmp_val = autodiff::val(tmp_obs);
+        tmp_grad = lf.gradient(tmp_val, i);
+
+#pragma omp critical
+{
+        lf.evaluate(tmp_val, i);
+        depth_der += tmp_grad*ders[0];
+        mass_der += tmp_grad*ders[1];
+}
+    }
+
+    return;
+}
+
+
+autodiff::var gobser_mass_depth_vz_sig(const gctl::point3dc &obsp, double loc_x, 
+    double loc_y, const autodiff::ArrayXvar& depth_mass)
+{
+    autodiff::var tmp_obs = 1e+8*GCTL_G0*depth_mass[1]*(obsp.z - depth_mass[0])
+		/pow(pow(obsp.x - loc_x, 2) + pow(obsp.y - loc_y, 2) + pow(obsp.z - depth_mass[0], 2), 1.5);
+
+    return tmp_obs;
+}
+
+#endif // GCTL_POTENTIAL_AUTODIFF
\ No newline at end of file
diff --git a/lib/potential/mkernel_block.h b/lib/potential/mkernel_block.h
index 3e1d3fc..a7afb35 100644
--- a/lib/potential/mkernel_block.h
+++ b/lib/potential/mkernel_block.h
@@ -35,6 +35,7 @@
 #include "autodiff/reverse/var.hpp"
 #include "autodiff/reverse/var/eigen.hpp"
 #endif // GCTL_POTENTIAL_AUTODIFF
+
 namespace gctl
 {
 	struct magblock_para