Abstract: after calculating the phases of Earth tide for the occurrence of 46 M_L5 earthquakes in North China, we found near 70% of the earthquakes occurred in π/2 or 3π/2 phase of Earth tide.It indicates that there are two special phases in the Earth tide with high probability of earthquake.This phenomenon shows that the earthquake is affected by the gravity of the sun and the moon, especially in the northern part of North China, though it may not be the direct cause.