Single phase VSC has a wide range of applications, and studying its operating characteristics is of great significance for harmonic generation mechanism, harmonic suppression and stability improvement. Firstly, the second-order generalized integrator is used to construct the synchronous phase-locked loop for the main circuit structure of single-phase VSC rectifier. Secondly, according to the requirements of DC voltage outer loop control and unit power factor operation, the equation of inner current control loop is established using the quasi-proportional-resonant controller. Thirdly, based on the linearization principle of the running trajectory of the time-varying period system, the harmonic transfer function matrix of the main circuit and control system is constructed, and the fifth-order admittance matrix model of VSC is deduced, and the influence of related factors on admittance characteristics and system stability is analyzed. Finally, the electromagnetic transient simulation model is used to verify the correctness of the analytical model and theoretical analysis.