GaN device has the advantages of fast switching speed，low on-off resistance，small parasitic parameters and low reverse recovery loss． As compared with other devices，it is more conducive to realizing the high frequency and high efficiency of bidirectional CLLC resonant converter． In this study，based on the characteristics of GaN de-vices，the resonance frequency of the bidirectional CLLC resonant converter was analyzed and calculated by using Thevenin equivalent theorem，and the condition to realize the soft switch was improved according to the charging and discharging characteristics of parasitic capacitance of switch tube． Finally，a bidirectional CLLC resonant con-verter based on GaN device was developed． An experimental prototype of bidirectional CLLC resonant converter with a rated power of 400W was built to achieve zero-voltage turn-on (ZVS) on the inverter side in all load range and zero-current turn-off (ZCS) on the rectifier side in a specific load range． Its maximum efficiency can reach to 97. 02% in the forward mode and 95. 96% in the reverse mode，and its maximum operating frequency is 548kHz．With features of high frequency and high efficiency，it verifies the correctness and effectiveness of the analyzed and designed converter．