In the process of digital observation, efficient observation means, reliable observation information and accurate calibration method are the important guarantees for observation quality. The ground water observation station of Yongan seismic station is unattended. Calibrate the water level gauge quarterly, according to relevant regulations. Observers check the water level every quarter. The calibration value is the basis for judging whether the water level gauge is working normally. In order to ensure the accuracy and efficiency of water level calibration, the author has developed a set of water level calibration device. It consists of two parts: a water level measurement module and a digital display module. It basically realizes the transformation from analog calibration to digital calibration. The device has been applied to the quarterly water level inspection of Yongan well. Compared with the measuring bell method used by Yongan station in the past, this device can reduce the error of water level calibration data to some extent, save working time and greatly improve the efficiency of calibration work.