To investigate the impact mechanism of different platoon control strategies on mixed traffic flow, this paper evaluates the overall performance of different heterogeneous platoon control strategies in smoothing small traffic disturbances and improving traffic safety. First, this paper derives the stability conditions for homogeneous and mixed traffic flow based on transfer function theory. Second, by simulating small disturbance experiments, the trend of speed under different traffic densities and the penetration rate of CAVs are analyzed. The characteristics of speed change coefficients under different platoon control strategies are comparatively analyzed based on the results in part 1. Finally, numerical simulation experiments were designed to analyze the safety performance of traffic flow under each strategy. The results show that (1) the combination of a variable time gap strategy with vehicle speed has the strongest ability to suppress disturbances. Among the combination spacing strategies, the combination of the variable time gap strategy with vehicle speed and the constant time gap strategy performs best in smoothing small disturbances. (2) At low penetration rates, incorporating CAVs may increase the instability of the traffic flow, while at high rates, CAVs effectively enhance the stability. These findings provide important guidance for selecting platoon control strategies in mixed traffic flow environments from the perspective of stability and safety.