This paper reviewed and analyzed the modulation ratio of the earth tides during 13 strong earthquakes above M6 in Chinese Mainland since 2009. The conclusions are as follows: (1) The strong earthquakes with M≥ 6 in Chinese Mainland occur frequently during the lunar phase, that is, they are obviously modulated by the solid earth tide; (2) The effect of tidal stress during the lunation is beneficial to the activities of strike slip and normal earthquakes, and the triggering effect on strike slip earthquakes is more significant. The effects of solid tide on seismic faults with different distribution modes and movement properties are obviously different; (2) Before the strong earthquakes with M≥6, the modulation ratio anomalies of small earthquakes near the focal area are widespread, including some small earthquakes occurring in the non-lunar phase period. Special attention should be paid to the phenomenon that the abnormal area of small earthquake's modulation ratio gradually shrinks to the epicenter and the abnormal area gradually decreases before the earthquake.