Aiming at the problems of traditional asymmetric half-bridge LLC converter in low-voltage DC power supply applications, such as large secondary current stress, uneven output current and difficult efficiency improvement, a dual transformer LLC resonant converter topology with symmetrical resonator is proposed, and the working status and characteristics of the symmetric resonator are deeply analyzed. The topology dual transformer structure can divide the resonant current in real time. The input current of the converter is continuous during the switching period and the current ripple is greatly reduced. The output current can be evenly divided and the output current stress can be reduced by paralleling the secondary sides. In order to further reduce the converter loop current, improve the converter efficiency and improve the traditional converter parameter design method, the converter gain model is established and the excitation inductance optimization curve is analyzed. The initial cavity parameters are designed considering the extreme working conditions of the converter, and then the precise time domain model of the converter is established to optimize the parameters. Finally, a 600 W converter prototype is built, and the experimental results verify the effectiveness and feasibility of the proposed symmetrical resonator double transformer topology and parameter design method. The maximum efficiency is 95.9%.