In order to improve the throughput of multi- channel cognitive radio (CＲ),a joint allocation algorithm ofsecondary user (SU) and transmission power for each sub- channel in the cooperative spectrum sensing is proposed.Based on the present state of the primary user,the proposed algorithm aims to maximize SU's total throughput overall the sub- channels subjected to the constraints such as SU's cooperative detection probability and total power,andachieves the joint allocation of SU and transmission power for each sub- channel through alternative direction optimi-zation.Simulated results show that the proposed algorithm helps to obtain the optimal value with less iteration andimproves SU's throughput by dynamically allocating the SU and the transmission power of each sub- channel accor-ding to the sub- channel state.