Abstract: For solving the near-far unfairness in cognitive radio system, the path gain factor was added on the pricing function in SIR-based (Signal-to-Interference Ratio) distributed non-cooperative game theoretic power control algorithm, and the existence and uniqueness of the Nash equilibrium are also proved. Meanwhile, based on this new power control algorithm, aiming at some secondary users’ SIR may be lower than the lowest threshold of SIR, a novel adaptive power control algorithm was proposed for cognitive radio system, and so, different secondary users’ SIR attain their individual SIR requirement. Simulation results show that the proposed algorithm can resolve the nearfar unfairness and regulate the transmitter power to meet the different SIR requirements of secondary users effectively, and furthermore, it can make different secondary users’ SIR satisfy the highest and the lowest threshold requirement of SIR with faster convergence compared with other classical SIR-based distributed non-cooperative game theoretic power control algorithms.