Abstract: In this paper, we proposed a modified non-stationary multi-input multi-output (MIMO) channel model for 3D mobile-to-mobile scenario. The continuity of fading phase between different channel states is taken into account, which can guarantee more realistic Doppler frequency shifts. Meanwhile, this paper investigates the time-variant spatialtemporal correlation properties of the proposed model. For the power angle spectrum (PAS) of the transmitter and receiver following Von Mises Fisher (VMF) distribution, the expressions of the spatial cross-correlation function (CCF) and temporal auto-correlation function (ACF) are derived. Simulation results of low-speed and high-speed scenarios show an excellent agreement between derived theoretical and simulated results. Our analytical expressions can greatly reduce the computational complexity, and significantly improve the efficiency of analysis and simulation of MIMO communication systems under complex and dynamic scenarios.