By comparing the topological characteristics of various DC/DC converters, an isolated bidirectio nal bridge DC/DC converter （BDC） with high power supply and transformer utilization and high power d ensity is selected; in order to improve the voltage gain and energy transmission efficiency, the resonant t ype is improved. BDC; in order to achieve consistent bidirectional operating characteristics and soft switc hing function, it is further improved to CLLC resonant BDC; in order to achieve constant voltage gain a nd transmission efficiency under frequency offset, a frequency tracking CLLC resonant BDC is finally de signed. The simulation results show that the frequency-tracking CLLC resonant BDC designed in this pap er can maintain high voltage gain and energy transmission efficiency under a large frequency range offset, no matter it is forward transmission or reverse transmission, and the bidirectional transmission characteris tics are basically Consistent.