Abstract: The space limitation of antenna disposition and CSI precision are the important factors that influence the performance of massive MIMO. Dual-polarized antenna can be widely adopted to accommodate a large number of antenna elements in limited space. However, CSI feedback schemes in LTE are not efficient for FDD based massive MIMO as feedback overhead increases almost linearly with the increase of antenna number. Moreover, the codebook will also be huge and difficult to design if reusing the LTE methodology. In this paper, a novel CSI feedback mechanism was proposed for dual-polarized antenna system to achieve better performance with low feedback overhead. The MIMO channel was decomposed into long term components (multi-path directions and amplitudes) and short term component (multi-path phases). The relationship between the two components and the optimal pre-code was also deduced in closed form. System level simulation results show that it can improve the performance considerably, improving feedback efficiency quantitatively and reducing the complexity of terminal.