In order to achieve high quality grid current output of inverter system, it is very important to eliminate the leakage current of the transformerless PV grid inverter. This paper analyzes the mechanism and current loop of leakage current, and based on dead-beat current control principle, illustrates the influence of leakage current on the inverter current and MPPT. It puts forward a kind of single-phase PV grid inverter leakage current compensation methods based on dead-beat current control. Simulation is carried out in Matlab/Simulink environment. The comparison between the model output and experimental measurement shows that using the compensation of the inverter duty ratio can efficiently eliminate the impact of leakage current on the inverter current, so as to avoid the misjudgment in power tracking or the condition that it can't find the maximum power point, in addition, achieve high-quality inverter current output and correct maximum power point tracking.