Abstract: A few years' continuous observation and investigation have been made of the static electric field in the atmosphere near ground surface at the Baijiatuan Seismic Station using different instruments since 1977. A relatively good correlation has been found between negative anomalies of the atmospheric electric potential gradient and local earthquakes through analysis and comparison. In other words, a relatively large negative anomaly of the electric field was recorded almost for each local quake of either ML4.0 with epicentral distance within 100 km or ML5.0 with epicentral distance within 250km, while no such anomaly appeared during earthquake-quiet periods. After the few years' observation and investigation we feel that it is possible to reveal a reliable precursor of earthquake through further study of the atmospheric static electric field.