The paper presents a grey predicting method for identify and estimate of AUV moving target based on the information of forward looking sonar. The region model of forward looking sonar is founded, the method of predicting moving target based on gray prediction principle is introduced, and the simulation research is carried out for three typical movement: regularity movement, accelerate regularity movement and variety accelerate movement. The result shows that the method can predict the information of the moving target fast and accurately.