Abstract: According to the properties of high-voltage impulse (HVI) track circuit, we use the least square (LS) method, the moving average (MA) filtering, and the MA filtering with endpoint smoothing on the basis of simulation model to smoothen the HVI signal. To eliminate the "end-effect", we propose a modified filtering method combining the MA filtering and LS method based on the comparison of the above three methods. Then, these four filtering methods are processed with a simulation model under random noise, periodic impulse interference, and Gaussian noise conditions. Compared with the other three methods, the modified filtering method improves the signal noise ratio (SNR), without requiring a large amount of calculation. Finally, the experimental results show that the modified filtering method is reliable and effective, and can be applied to identify and detect HVI signals in an HVI track circuit system.