Abstract: The spatial encoding technique is one of the key techniques in 3D measurement. The spatial encoding method,which plays an important role in resolution, speed and reliability in measurement,is introduced. The measurement principle of structured light method based on a triangular algorithm is described. The influence and functions of spatial encoding technique are studied, the principle of encoding is introduced and the condition which should be satisfied by the encoding scheme are summarized. Several typical encoding methods investigated in recent years and the stripe boundary encoding proposed by this laboratory are analyzed and compared. Their advantages, drawbacks and development trend are introduced. The proposed colorencoding methods, their unique advantages and common drawbacks are introduced. Finally, based on the study, the spatial encoding technique is reviewed and its prospect is pointed out.