In this paper, we propose a robust pre-coder design method for Cognitive Radio Multi-Input Multi-Output (CRMIMO) system under the consumption that the channel state information (CSI) estimations are imperfect from secondary base station (SBS) to primary user (PU) and secondary user (SU). Due to the uncertainties of the channel estimation error, both the outage probability of the received SNR of SU and the outage probability of the interference of PU are considered in pre-coder design to minimize the total transmitted power of secondary base station. The Karush-Kuhn-Tucker conditions of the proposed pre-coder scheme are analyzed as well. Simulation results show the effectiveness of the proposed pre-coder scheme.