Aiming at the problems of unclear physical mechanism and immature modeling and simulation techniques for grid-connected gravity energy storage systems, a comprehensive modeling and simulation method incorporating the mechanical subsystem of gravity energy storage, a permanent magnet synchronous motor (PMSM), and a grid-connected converter is proposed. First, based on the energy conversion principles of gravitational potential energy and electric energy, the energy flow, kinematics and power models of gravity energy storage are established to quantify energy losses and dynamic power characteristics under charging and discharging conditions. Then, the mathematical model of the PMSM in the d-q reference frame is developed. A zero d-axis current control scheme is designed for the machine-side converter, while the grid voltage-oriented vector control scheme is designed for the grid-side converter, to realize precise control of motor torque and grid-connected power. Finally, a simulation model of the grid-connected gravity energy storage system is built on the MATLAB/Simulink platform. Simulation results show that the output power of the gravity energy storage system can accurately track variations in required grid power, with highly sinusoidal voltage and current waveforms, fast responses of motor speed and torque, thereby verifying the effectiveness of the proposed modeling and simulation techniques for grid-connected gravity energy storage systems.