<p>Power electronic inverters, particularly in systems with high renewable energy penetration, often encounter stability challenges due to their inherent characteristics of low inertia and weak damping. This paper focuses on a hybrid system composed of grid-following and grid-forming inverters, conducting stability analysis and proposing an effective stability enhancement control strategy. First, a sequence impedance model of the hybrid inverter system is established. To ensure the accuracy of the model, frequency sweep analysis is carried out for validation. Subsequently, an impedance ratio sensitivity method is employed. This method is used to quantitatively evaluate the influence of various parameters on system stability, including the phase locked loop and current loop parameters of the grid-following inverter, as well as the power synchronization parameters and the double control loop of the grid-forming inverter. Based on the results of the sensitivity analysis, a virtual impedance strategy is designed. This strategy uses the amplitude margin as an indicator and adapts to different short-circuit ratios. Finally, the correctness of the impedance sensitivity calculation results and the effectiveness of the virtual impedance strategy are verified through simulations in MATLAB/Simulink and experimental results.</p>