Abstract: By compution of several practical examples,it is proved that the moment method's stability is very different for the different selection of bass function.So it is possible to improve the moment method's stability by select the appropriate bass function. Besides ,by selecting the multi scale sub domain bass function and superposition algorithm,the coefficient matrix's condition number can be reduced,so can be the requirement to the computer's memory.It is proved by several examples that the superposition algorithm for moment method's solution on the multi scale sub domain function bass is an effective and stable method.