An axial piston pump is a key component that plays the role of the“heart”in hydraulic systems.The pump failure will lead to an unexpected breakdown of the entire hydraulic system or even economic loss and catastrophic safety consequences.Several vibration-based machine learning methods have been developed to detect and diagnose faults of axial piston pumps.However,most of these intelligent diagnosis methods use single-sensor vibration data to monitor the pump health states.Additionally,the diagnostic accuracy is unacceptable in most situations due to the complex pump structure and limited sensor information.Therefore,this study proposes a multi-sensor fusion method to improve the fault diagnosis performance of axial piston pumps.The convolutional neural network receives three channels of vibration data and makes the final diagnosis through information fusion at the decision level.The proposed decision fusion method is evaluated on the classification task of leakage levels of an actual axial piston pump.The experimental results show that the proposed method improves the classification accuracy by adjusting the probability distribution of classification according to the learned weight matrix.