The invention provides a cognitive radio power control method and system based on adaptive bacterial foraging. The method includes the steps of establishing a multiuser underlying distributed cognitive radio network system, and setting initial values of parameters of the cognitive radio network system and initial values of parameters of an adaptive bacterial foraging algorithm; and then determining whether the transmitting power of current cognitive users meets preset constraints, and controlling the power of the cognitive users using the adaptive bacterial foraging algorithm to obtain the minimum value of the sum of the transmitting power of the cognitive users. According to the invention, the communication quality of the authorized users can be guaranteed, an adverse effect of the transmitting power of the cognitive users on a cognitive device is avoided, the cognitive users are allowed to have less energy consumption, the run time of the network is extended, and a better cognitive network spectrum utilization rate is thus gained.