The high-order finite difference algorithm is adopted to calculate the reverse time migration in this paper, and low-frequency noise suppressing approach by Laplace operator noise-eliminating filter is mainly focused. Comparing with the conventional high-pass filter approach, the reverse time migration (RTM) denoising test on Marmousi model shows that Laplace operator denoising approach can effectively suppress the low-frequency noise: not only preserve the properties of amplitudes and phases of those effective signals, but also obviously improve the imaging effects of the profiles.