Frequency interference is the most common form of interference signals in all kinds of information equipment and signal processing. If the frequency interference is not removed, it would affect the measurement accuracy. In the beginning, the frequency interference on the impact of the analog signal was analyzed, then according to the characteristics of interference, a control circuit to control sampling frequency was designed, and the sampling frequency and frequency synchronization were realized, and so as to effectively remove the frequency interference. Finally by the method of calibration, the ideal mathematical relationship of the output values and the input analog signal were obtained.