In view of collocated MIMO radar tracking multiple moving targets, this paper proposes a power allocation method based on the Posterior CramerRao Lower Bound(PCRLB). In this method, firstly, the PCRLB of multiple moving targets localization localization errors is given as a cost function for power allocation. Thus, the radar power allocation is transformed into a convex optimization problem. Then, the SDP algorithm is used to deal with the convex optimization problem to transform it into a SDP problem and solve, realizing the optimal allocation of radar power. Finally, the validity of the proposed algorithm is verified by simulation. The results show that compared with the average power distribution and a greedy algorithm based on maximum SNR, the tracking accuracy of the target is obviously improved by the optimal power distribution method.