Abstract: Compared with the L filter,the LCL filter is more suitable to the high-power application for the better attenuation characteristics in high frequency harmonic electric current.However,the parameters design for LCL filter is more complex since both the inhibit effect of high frequency harmonic electric current and the influence of controller’s performance should be considered.In this paper,the mathematic model of LCL filter and the limiting conditions for all the parameters of filter are firstly studied.Then the impact of all parameters of LCL filter on system is intuitively drawn on the same plane using curves by theoretical derivation.Finally,a parameter design and optimization method for LCL filter is proposed based on the graphic analysis.An example of LCL filter design on single-phase shunt active power filter（SAPF） is presented;meanwhile the validity and effectiveness of the proposed method are proved by simulations and experiments at the end of paper.