For predicting the running-in process of wet clutch test，a method based on multifractal spectrum and its parameters are proposed to predict the running-in state，combining with the geometry features of friction torque signal in test. Firstly，the concept of multifractal spectrum based on the box-counting method is introduced；and then the inherent relationship between the multifractal parameters and friction torque is discussed；finally，friction torque signals from a certain type wet clutch running-in test are analyzed and depicted by the multifractal spectrum and its parameters. The analytical results show that the geometry features of friction torque signals can be quantitatively described through multifractal spectrum and its parameters，and the breadth and fractal dimension difference of maximum-minimum probability subset of multifractal spectrum gradually decrease with the running-in process，while the minimum singularity exponent increases gradually with the running-in process. Therefore the running-in state of wet clutch can be effectively predicted by the multifractal spectrum of friction torque in test.