Abstract：Based on the catalogue of small earthquakes in China, using the temporal and spatial scanning method of earth tide modulation ratio, we analyze the temporal and spatial variation characteristics of earth tide modulation ratio before moderate-strong earthquakes in the capital circle area of China since 1987. The results show that seven of the nine earthquakes (MS≥5.0) present abnormal modulation ratios, which occurred within 1 a before the main shock and within 100 km from the epicenter. The seismic correspondence ratio is 78%. The abnormal high value intensity usually lasts about 3~5 months. Most disappear in the months before the earthquakes. The analysis of the earth tide modulation ratio shows a good earthquake reflecting ability, and it offers a useful reference for the prediction of moderate-strong earthquakes in the capital circle area of China.