Abstract: Now with the development of the research of the motion capture and the behavior understanding of the human,the demand is increasing．The people extracted the articulation points as the feature points manually before,compared with that.How to make the extraction of the feature points much more automated is meaningful to the research of the motion capture and the behavior understanding later．This paper proposed the method of extracting the dynamic human’s articulation points and obtaining the position of the articulation points on the first frame image automatically from monocular video sequences to solve the disadvantage of traditional method about extracting the points from marked human body manually．Then the points were tracked with the light flow sparse L_K algorithm to acquire the information of two-dimensional coordinate about the moving human．Finally,combining the camera model the relative depth of the points can be obtained through geometric calculation.

Key words: Articulation points,Scaled-orthographic camera model,Scale factor,Reconstruction