Abstract: This paper proposes a safety variable time-gap (SVTG) spacing strategy for autonomous adaptive cruise control (ACC) vehicles, which takes the vehicles velocity and maximum deceleration into account. The vehicle safety, the stability of the individual vehicle, string stability, and traffic flow stability, and the traffic flow capacity can be improved by the proposed spacing strategy. The SVTG spacing strategy solves the limitation of traffic flow instability of constant time-gap (CTG) spacing strategy and the shortcoming of unsafety of the variable time-gap (VTG) spacing strategy. The simulation results show that the performance of SVTG spacing strategy is better than the other two spacing strategies.