Abstract: For thruster fault diagnosis of an AUV(autonomous underwater vehicle) based on multi-AUV system(MAUVS),a method to simulate sonar sensors is proposed.The output characteristics of AUV’s sensors before and after fault are analyzed,and a temporal or spatial fault probability fusion method is proposed.A basic probability assignment(BPA) function is proposed based on speed residual value and angle residual value.The method of fusion rhythm of time and evidence is improved in consideration of the uncertainty of detection method based on probability.The AUV pool experiment results prove the validity of the proposed information fusion fault diagnosis method in improving reliability of fault evidence,real time performance of fault detection and diagnosis efficiency.The presented method provides an optional scheme for the thruster fault diagnosis of MAUVS.