The interest of this paper is to propose a Gray Markov (GM) model for earthquake prediction with the example of the 2008 Wenchuan aftershocks occured in the area of southern Shaanxi provinces. The aftershocks data are fitted for a preliminary prediction based on GM (1, 1) model. The results of preliminary prediction are revised using Markov model's state interval and state transition matrix. The next group of earthquake data are used to predict based on Gray -Markov model. It shows that the method is more accurate. The results show that the predicted values and real values are in a good match. Then, the predicted values and real values are also very close. This method can be recognized as practicality in earthquake prediction, even in the field of weather forecast.