Charge pump is an important module in analog phase -locked loop. The mismatch current greatly affects the in-band noise of CPPLL. To reduce the charge pump mismatch current to improve the overall noise performance of the PLL. In order to reduce the influence of channel length modulation effect on current source, a compensation current is added to the current source of traditional charge pump, and the current is determined by feedback loop. The simulation resultsshow that when the output voltage ranges from 0.4V to 2.8V after the addition of the structure, the charge-discharge mismatch ratio decreases from 7.9% to 0.34%. Thus, the noise performance of the PLL is greatly improved.