High penetration rates of renewable energy may trigger safety and stability issues in power grid operation, such as voltage/frequency fluctuations and even grid disconnection. To leverage the advantages of both grid-following (GFL) and grid-forming (GFM) control technologies, this paper proposes the application of a GFL-GFM converter hybrid system in renewable energy grid integration systems. However, the impact of capacity allocation and key parameters in the GFL-GFM hybrid system on renewable energy integration stability under different grid strengths requires further investigation. Therefore, this study focuses on how the GFL-GFM converter hybrid system supports renewable energy grid stability. Firstly, the fundamental framework of the hybrid system is introduced. Secondly, the control characteristics of both GFL and GFM converters are analyzed. Based on this, the influence patterns of power allocation and key parameters of GFL/GFM converters on renewable energy integration stability under various operating conditions are explored. Finally, a simulation model of the hybrid system is developed using MATLAB/SIMULINK software platform for validation.