As the installed capacity of grid-following renewable power grows significantly, the risk of system oscillations is increasing. Compared to the past, where large-scale renewable power bases are sent out centrally leading to the instability of the farm-network mode of action, the decentralized integration of large-scale new energy into the receiving grid at multiple points may result in more pronounced interactions between different wind farms. Based on characteristic pattern analysis, the dominant oscillation mode of multi wind farms decentralized access multi region weak AC interconnection system is determined in both field- network interaction mode and inter fields interaction mode. Then, the impact of wind power control parameters and system operation mode on the stability of the dominant oscillation mode of the system is studied. Analysis shows that the control bandwidth of each wind farm tends to be synchronized and the coupling effect between wind farms is more obvious. On the other hand, the differences in electrical distance and operating conditions between wind farms can affect the interaction between them. Detailed electromagnetic transient simulations based on PSCAD/EMTDC verifies the correctness of the analytical conclusions. The research work has certain guiding significance for understanding the control interactions among multiple wind farms, guiding the site planning of wind farms in complex systems and proposing oscillation suppression strategies.