Abstract: In order to extract the internal and external surface point clouds of the turbine blade with high accuracy,a contour tracing method based on the 3 D-ICT images of the turbine blade is proposed.The techniques to deal with the fake closed contours,isolated points,contour segments during contour tracing and refinement are analyzed.In order to improve the accuracy of the contour coordinates,a moment matching contour tracing algorithm is introduced,which achieves the sub-pixel accuracy.The experimental results prove that through this method,the ordered,dense and accurate point cloud data of the internal and external surface are finally obtained.