The block stability based on earthquake time-history curve is studied by computation program. Vector analysis of block theory is adopted for programming. The detailed approach involves the following procedures: input the required information of structural planes and free faces, and subsequently determine the finiteness and mobility of the block according to finiteness theorem and mobility theorem. If the block is movable, find out the sliding mode of the block (single face sliding or double face sliding) under the combined action of dead weight and seismic loads. Finally compute the safety factor under that sliding mode and draw the time-history curve of dynamic safety factor. In addition, a block drawing program is added to obtain information regarding the contact area between each face and the volume of the block required for the computation when the cohesion between the blocks is considered.