Abstract: There is generally an exceedance problem in the calibration for vertical pendulum tiltmeter.The main reason to the problem is that the calibration value we choose is improper, in which the tidal variation in calibration voltage is not eliminated.Here a new method to choose the calibration value is presented.This method can eliminate the tidal variation and high frequency interference, and is developed into program.After operation in Zhangjiakou, Huailai, Yangyuan and Chicheng Seismostation, the program reached the expectation in precision.