Abstract: Collect, put our country (mainly the continent area) from 1966 to August of 2002 in order on the foundations of 183 M≥5 earthquake array materials, use gray predict and method of least square fit predict to examine and predict rigidly stronger aftershock when to take place of every earthquake array.The result indicates, two kinds of prediction methods have better prediction efficiency to stronger (remarkable) aftershock of M≥7 earthquake array and 6 magnitude of earthquake array, predict efficiency is 76.2% and 64.7% respectively;Predict to 5 magnitude of earthquake array the result is not very obvious.So gray predict and the method of least square focus on the heavy earthquake stronger aftershock predict mainly, expect to play a positive role in an urgent need work after stronger (remarkable) earthquake in scene.