Because of the space-diversity and waveform-diversity, large virtual transmit-receive channels are established in statistic MIMO radar. Various methods are used to cope with the channel coefficients of MIMO radar in different papers when estimating the parameters of the targets. To evaluate the channel parameters’effects on MIMO radar estimation performance, two most popular methods are summarized in the paper, and three topical models of channel coefficients are proposed according to the two methods. We derive the MLE and CRLB for the three models respectively. The estimation performance of the three models are compared through simulation. Simulation results show that we can get higher estimation accuracy if the channel coefficients are jointly estimated with the target parameters. But if the other method is used, the estimation accuracy will become worse,the divergence of estimation accuracy between the two methods will increase with the SNR.