diff --git a/gmtsph-global.sh b/gmtsph-global.sh
index ea31cd2..383e909 100755
--- a/gmtsph-global.sh
+++ b/gmtsph-global.sh
@@ -94,7 +94,7 @@ else
 	#-C${cptfile}+Uk 使用km（色标单位除1000
 	#如果unit等于km则在cptfile后面添加+Uk
 	if [[ ${unit} == 'km+Uk' ]]; then
-		gmt psscale -Dx0.4i/-0.3i+w1.2i/0.05i+h -C${cptfile}+Uk -Bxa -By+l${unit} -O >> $psfile
+		gmt psscale -Dx0.4i/-0.3i+w1.2i/0.05i+h -C${cptfile}+Uk -Bxa -By+l"km" -O >> $psfile
 	else
 		gmt psscale -Dx0.4i/-0.3i+w1.2i/0.05i+h -C${cptfile} -Bxa -By+l${unit} -O >> $psfile
 	fi