The invention discloses a symmetrical half-bridge LLC resonant bidirectional DC-DC converter, which belongs to the technical field of power electronic application. Topological structures on the two sides of the converter are symmetrical, and adopted components adopt a complex function design. When a switching network and a resonant network on one side of a high frequency transformer function, the switching network and the resonant network on the other side are automatically evolved into a rectifier-load network, and the networks on the two sides commonly form the whole LLC resonant converter to realize power conversion in a corresponding direction. Because the structures are completely symmetrical, reverse conversion can be possible; and in the reverse conversion, the topological structures can be automatically reconstructed to form a reverse LLC resonant converter to realize reverse power conversion. The symmetrical half-bridge LLC resonant bidirectional DC-DC converter achieves effective improvements in conversion efficiency, power density, dynamic performance and electromagnetic compatibility, reduces the electrical stress of components at work, has a reduced volume and a reduced weight, and realizes highly-efficient, isolated and bidirectional DC/DC power conversion.