Abstract： A model was established to describe the response signal excited by reciprocating inertia force. The parameters of the model were identified by the pattern recognition method. The processing results of the experiment data from a 195 diesel engine indicate that the influence of the instantaneous speed could be ignored. A fourthorder model is appropriate to describe the response signal and the data of early stage in compression stroke is suitable for identifying the model parameters. The trend of the processed internal combustion engine vibration velocity remains consistent with that of the pressure rise rate and the correlation between them is improved, which verifies the proposed method.