In order to solve the problem of high mismatch rate of local matching algorithm,a semi-global matching algorithm based on AD-Census transform and multi-scan line optimization is proposed.Fir stly,the initial matching cost is calculated by combining the absolute difference AD algorithm with the Census transform as the similarity measure function.At the same time, building dynamic cross-domain is to aggregate matching cost.Secondly,matching cost aggregating for one-dimensional dynamic programming is extended to the multi-scan line optimization.The calculation of matching cost aggregation is performed by successive scanning in four directions of up,down,left,and right,and introdu cing a regularization constraint algorithm is to ensure consistency of matching cost aggregation,which can reduce the a large nu mber of matching abnormal points of the initial matching cost in the cost aggregation calculation stage.Finally,the Winner-Ta kes-All algorithm is used to select the parallax corresponding to the pixel when the cost aggregation is minimal,and the left an d right consistency detection algorithm and parabola fitting algorithm are used for subsequent processing to improve the cor rect rate of stereo matching in the parallax refinement stage.Experimental results show that the algorithm proposed in this paper can obtain dense disparity map with high matching rate and less time consuming.