Abstract: In this paper, a fast algorithm to extract surface boundary is proposed on the basis of the triangular mesh data. Boundary stack is constructed, and all boundary index push back into the boundary stack and an empty boundary pool are initialized. One boundary index is popped up from the boundary stack and compared with all indexes in the boundary pool. If there is same one boundary index that is viewed as inner boundary, then it deletes it from boundary pool, else, makes it stay in pool. It repeats the above steps until the boundary stack is empty, and the process of boundary detection is finished. The boundary is stayed in boundary pool. Experimental results show that the new algorithm is simple to implement, and has high computing efficiency.