Vehicle-to-vehicle (V2V) communication system is an important part of the future intelligent transportation system, and its non-stationary characteristics have been verified in channel measurement. A non-stationary double-ring geometry-based stochastic model is proposed for V2V multiple-input multiple-output communication systems. In order to describe the non-stationarity of the channel, the time-varying characteristics of the angle of arrivals (AOAs) and the angle of departures (AODs) are introduced into the model, the time-varying statistical characteristics such as the spatial cross-correlation function (CCF) and the time autocorrelation function (ACF) of the model are derived. In addition, based on the modified equal area method ( MMEA), the corresponding simulation model is developed. The effects of scattering environment, moving state of mobile terminal and antenna deflection on channel statistical characteristics and non-stationarity are studied. Simulation results show that the proposed model can effectively simulate the nonstationarity of the V2V channel and the statistical characteristics of the channel under stationary state are consistent with those of the stationary double-ring model, which verifies the correctness of this model.