A method for cancelling pseudo mode function in empirical mode decomposition (EMD) is presented based on energy conservation. The properties of pseudo mode function are investigated on the relation between EMD error and the pseudo mode function under normal sampling. Using the completeness, energy conservation and properties of EMD, the principle of mode function cancellation is proposed for ticking out the pseudo mode functions from the decomposition results and cancelling the error in the intrinsic mode function. Moreover, an example illustrates the validity of the method. The research study has theoretical value and engineering significance for EMD processing at high accurate level under the condition of unreasonable sampling.