When photovoltaic panels connect to the grid through grid-tied inverter, leakage current will appear in the system due to the stray capacitance of photovoltaic panels if no isolation measures are taken, which will result in great harm. Thus, this paper proposes a method of leakage current suppression of three-phase transformerless photovoltaic grid-tied inverter based on virtual resistance. First, this paper gives the state-space model of grid-tied inverter, and analyse the cause of system leakage current. Second, based on the above analysis, virtual resistance method is adopted to suppress leakage current and the design guideline of virtual resistance is given. Finally, the proposed method is verified by simulation results.