This paper proposes a new Frequency Adaptive Repetitive Control (FARC) approach for grid-connected inverter with LCL filter, which utilizes all-pass filter to approximate the delay unit of the frequency ratio’s fractional parts of the repetitive controller. When the frequency varies, it makes the resonant frequencies of the internal model of repetitive controller be close to the practical grid fundamental and harmonic frequencies by tuning the coefficients of all-pass filter on-line. The proposed approach can achieve the effective suppression of harmonic in grid and ensure that the inverter output high quality grid-connected current when frequency varies. The design processes of FARC and system stability analysis are given in detail. Simulation and experimental results verify the effectiveness and feasibility of the proposed control approach. This work is supported by National Natural Science Foundation of China (No. 51207086).