Abstract: MIMO (Multiple-Input Multiple-Output) radar has evident advantages in target detection, parameter estimation, and so on. The Cramer-Rao Bound (CRB) for parameter estimation is proved to be a useful tool for characterizing system design and STAP performance. Therefore, based on MIMO radar with collocated antennas utilizing orthogonal frequency division signal, the space time frequency signal model of target and clutter is given to be used in MIMO radar first. On the basis of the model, the CRB of the ML estimator of ground moving target angle and Doppler for MIMO radar are deduced based on STFAP. Finally, through simulation of CRB performance, it is demonstrated that MIMO radar is effective in eliminating velocity blind zones and improving target parameter estimation accuracy.