With the consideration of the effect of harmonic and threephase unbalance on ripple and the superposition of ripple in AC side grid, the ripple problem in AC/DC hybrid micro grid is studied in this paper. Firstly, It is proposed that if the phase angle of the korder harmonic source changes in its three phases, the amplitude of the k+1 and k1 ripple generated by the kth harmonic source is the reciprocal relationship,which has an impact on the superposition of ripple.Then, it is found that the effect of the initial phase difference of harmonics on the amplitude of the superimposed ripple has a certain regularity by superimposing the positive order harmonics of the same number, the negative order harmonics of the same number and the positive order and negative order harmonics of adjacent times.Finally, the above studies are confirmed by Matlab/Simulink modeling. It is shown that the amplitude of ripple superposition in ACDC hybrid micro grid is related to the harmonic frequency and initial phase difference of harmonic source. The research of this paper is of great significance to the analysis and management of power quality in hybrid micro grid.