The invention discloses an inner loop controll analytic transfer function modeling method and system for a voltage source converter grid-connected system. The method comprises the following steps: building a power grid intensity and phase-locked loop dynamic-considered voltage source converter grid-connected system mathematical model based on a first hypothesis condition; linearly processing the voltage source converter grid-connected system mathematical model; acquiring an inner loop controll simplified transfer function of a current based on a second hypothesis condition; materializing an output phase expression of a phase-locked loop dynamic according to the simplified transfer function, and building a phase-locked loop dynamic influence-considered inner loop controll analytic transferfunction of voltage source converter grid-connected current; and analyzing an inner loop control instability mechanism of the voltage source converter grid-connected system based on the inner loop controll simplified transfer function, and instructing parameter design.