The time sequence curves and spatial isolines of mobile gravity observational values from the Wenba net in Hebei province are drawn, and the response of gravity observation to earthquakes in the net and its surrounding area is analyzed. The gravitational anomalies showed the following characteristics： the anomalies might last out about 2 years, and its magnitude can reach tens μg; most anomalies showed continually decreasing and turning before earthquake; some high value region appeared in the gravitational field of Wenba net before Xingtai M5.4 and Wen＇an M 5.1 earthquakes; the epicenter of Wen＇an earthquake located near the 0 isoline of high grads region.