This paper introduces an effective method to identify and cancel a pseudo mode function in empirical mode decomposition (EMD) under the condition of insufficient sampling rate. The contents of this paper have three aspects: First, basic properties of the pseudo mode are accurately revealed. Second, a post-processing technique for EMD is developed. This new technique, called as mode function cancellation, can identify and kick out the pseudo mode from the decomposition results, and correct the decomposition error in the intrinsic mode function. As a result, it can help us to improve the decomposition’s accuracy. Finally, for a mixing mode, the energy of pseudo mode function is proposed on the cross-correlation at time zero, and it can be used to measure the ratio of signal mode to pseudo mode. Examples and experimental data are illustrated to prove the validity of the presented approach. The research results show that this approach can improve EMD performance while a pseudo mode occurs in the decomposition.