Abstract：Based on the topology principles and literatures，the “oriented” theorem is extended and the “closed”theorem is brought forward. The former means edges，loops and blocks are all of orientations. The latter means every edge in a block is attached to two loops with directions being converse in the edge. All loops are used twice times during block identifications；and the total volume of all positive and negative blocks is zero. Then，by procedures of 3D discontinuities network simulation，intersecting lines and primary loops analyses，deleting isolated loops，relative loop analysis，and closed block identification，the general method of spatial block topological identification is put forward. The criteria of validity check are presented simultaneously. Case studies and validity examinations show that the method can correctly and effectively search a great number of blocks(including concaves) with complicated figures formed by numerous finite discontinuities，and indicate that the method is universal and reliable.
