For the large-scale grid-connected PV inverter system, the total inductance of the LCL filter is directly related to the size and cost of the system. Therefore, a LCL parameters optimization design method is proposed to make its total inductance minimum meeting the filtering performance requirements. The consumption of reactive power of the capacitance branch and the amplitude ratio of the injected harmonic current to the corresponding frequency harmonic voltage are set as filter performance appraisal parameters in this method. By introducing the split ratio parameter of the high frequency harmonic current of capacitance branch and the grid side inductance branch to the high frequency harmonic current, the functional relationship between the total inductance and the main design parameters is established, and the parameter condition of minimum total inductance and its solving method are given. The design example and simulation verify the practicability and availability of the proposed design method.