To solve the problems of poor transient stability and difficulty in fast frequency regulation of a large number of renewable new energy sources connected to the power grid, this paper proposes a fast frequency response control and transient stability analysis method for energy routers. Firstly, in response to the transient instability problem caused by the frequency modulation control strategy of existing energy routers (small hydropower, photovoltaic, energy storage, and grid connected ports), this work first analyzes the control method of energy routers, and combines T-S fuzzy modeling method to derive the transient model; Then, the transient instability and stable operation mechanism of energy router are studied. It is found that the existing frequency modulation control strategy of the energy router has a small attractive domain and the system is prone to high-power disturbance instability. However, the proposed fast frequency response control strategy of the energy router can ensure a larger attractive domain and stable operation of the system, providing theoretical guidance and technical support for the fast frequency response and transient stability control of energy router under frequency modulation conditions; Finally, the correctness of the proposed fast frequency response control and transient stability are verified by simulation.