Mode mixing is an inevitable problem in empirical mode decomposition ( EMD), the ingredients which cause mode mixing, such as intermittency, pulse and noise, are defined as abnormal events in the paper. A novel method using high frequency harmonic before EMD is proposed. The amplitude and frequency of the a dded harmonic are determined according to frequency range and characteristic of the original signal, and the added harmonic will be decomposed as the first IM F, then mode mixing can be alleviated. Commonly the first IMF containes the ad ded harmonic and the abnormal events, the harmonic can be subtracted to get th e true first mode if necessary. Compared with EEMD, simulation results show th at both the two methods can avoid the mode mixing correctly, but the proposed method allows small errors, fast operation, tangible physical meaning and no post-process. An actual fault signal with complex abnormal events is also analyz ed, and the effectiveness and feasibility in engineering are verified.