Large harmonics can be generated when distributed PV is connected to distribution network, initiating system resonance and damaging distribution network operation. To solve this problem, this paper establishes grid inverter equivalent model and analyzes the causes of resonance. On this basis, an improved deadbeat control strategy is proposed to improve the harmonic suppression effect. By predicting k+2 sampling current, it overcomes the shortcomings of the traditional deadbeat control delay and the poor response of the current closed-loop control. Then, it combines with the virtual harmonic impedance method, increases the output current bandwidth, reshapes the output impedance of the inverter, and destroys the resonant forming condition. Through system experiment verification, the results show that the method is effective to inhabit resonance. This work is supported by National Natural Science Foundation of China (No. 51707089), Science and Technology Project of Headquarter of State Grid Corporation of China (No. 52020116000D) and Science and Technology Project of State Grid Jiangsu Electric Power Company (No. J2017038).