Of late years, steady performance of two sensor hierarchical fusion algorithm with non-full-rate communication was evaluated by Chang K.C., the result indicates that the performance of the algorithm with complete feedback is not so good as that of the algorithm with partial feedback and moreover, in the case of complete feedback, the increment of data rate does not improve the performance. In the research, more attention is paid to the effect of the number of sensors on the steady performance of the algorithm with different feedback mechanism. It shows that for the algorithm with complete feedback, in the case of process noise being relatively small, the increase in the number of sensors does not improve but worsens the performance. This conclusion is an extension and development of the work by Chang K. C.