The conventional fault diagnosis method of cab abnormal jitter mostly uses neural network algorithm, which ignores the correlation between fault data, making the diagnosis accuracy low. For this reason, a diagnosis method of light truck cab abnormal jitter under specific speed is proposed. The data collector is used to collect the online information data of the cab, classify the data periodically, analyze the internal relationship between the fault data, analyze the collected information data, judge the operation state of the vehicle cab, and use the fault tree method to calculate the probability importance of the bottom event, thus realizing the cab shake fault diagnosis. The case test results show that the proposed method can diagnose cab jitter fault with high diagnostic accuracy.