Abstract: The spontaneous potential field, an important component of the geo-electric field, is a natural electric field, which is formed by the physical and chemical effects of the earth medium. From 2016 to 2017, an whole-directional observation test of the spontaneous potential field was carried out in the Chongzhou seismic station. The test results show that: ① the observation system is reliable, with the results of the zero input synchronous test meet the requirements of the maximum permissible error, and the results of the electrode potential test meet the basic requirements of the long-term stability; ② the results of experimental observation can basically reflect the changing characteristics of spontaneous potential field in the test area, with good consistency and relevance, which compared with the results of the multiple device in the same direction; ③ the great difference was found in the results of the spontaneous potential field from the different directions, with the main reason as the complicated influence factors from the earth surface. The further study shows that, it has a great additional influence on the spontaneous potential field observation with the result of the filtering action, when the horizontal seepage of the surface water was existed, and it has particularly obvious with the complex topography especially.

Key words: Spontaneous potential field, Whole-directional observation, Influence factors, Chongzhou seismic station