This paper discusses in detail the calculatiou and analysis of rockmass stability in Changpo Mining District, which is an important part of the CNNC (China National Non-ferrous Corporation) key scientific research project titled The Ground Pressure Active Patten And Mined-Out Area Treatment Technology Research In Chargpo Tin Mine, By using two-dimens- ional and three-dimensional elastoplastic finite element programmes, the results of calculation and analysis showe that: (1) for large and thick steeply dip orebody, horizontal thin plate pillars (top and bettom pillars) will play a less significant role than vertical pillar; (2) single excavation provides better stress conditions than multi-excavations; (3) for a sublevel, the downward mining sequence is superior over the upward; and (4) for the adjacent orebodies, the rightward mining sequence is better than the left-ward.