Abstract: In order to solve the difficulty of coal seam TIN dealing with reverse faults,a new algorithm of con-strained Delaunay triangulation is proposed.The TIN built by the algorithm,on the one hand meets constrained Delaunay principle,and on the other hand is a good solution for formation of TIN of reverse faults.The algorithm,checked by various coal geological data with complex normal/reverse faults and fault combination,is simple,high-efficient,and useful for automatic creation of coal roof/floor contour map in the future.