Aiming at the problem that the lack of supporting algorithms for shape measurement using micro-nano scale 3 D scanning electron microscopy（SEM）

leads to its application is severely limited. a 3 D measurement method based on parallax-depth mapping is proposed. Firstly

a mapping model of parallax and sample surface depth information is established. The polar line correction algorithm is introduced to ensure the accuracy of the parallax solution. Corresponding points are matched based on optical flow estimation

to obtain a dense and accurate disparity map

which ensures the quality and precision of 3 D data. Finally

in order to prove the validity of the proposed micro-nano-scale 3 D surface measurement method

compare it with the super-depth 3 D microscope which is more commonly used in the field of micro-nano testing. The two methods are used to measure and characterize the sample in 3 D. The results show that the proposed method is effective and reliable.