Abstract: This paper introduced D-S evidence theory in evaluation of coalbed methane reservoirs to solve the uncertainty problem due to randomness, faintness and data lacking of reservoirs parameters in evaluation of CBM reservoirs. The evaluation model of CBM reservoirs is set up based on evidence theory and the detailed arithmetic of evidence theory is brought forward, and according to some decision making rule the coal reservoir in south of Qinshui Basin has been evaluated, and the best favorable area for CBM development has been affirmed. The results show that the model can solve the problem of uncertainty and make evaluation results more reliable and precise.