In this paper,we have computed the correlation between the seasonal velocity variations of earth rotation and the seasonal frequent curves of strong earthquakes.The correlative coefficient is related to the earthqua-ke magnitude.And we found that the latitude distribution of strong ear-thquakes relates to centrifugal force,hence we have found some evidence about earth rotation inducing earthquakes.We have also analysed the relation between short cycle of earth rotation and earthquakes,according to the anomaly of underground water and the forerunner of earthquakes measured by laser lock-paper strain instruments.