A high frequency high voltage gain coupled-inductor Boost circuit based on planar component is presented in this paper. GaN switch is adopted with lower conducting resistance and higher switching speed. Zero voltage switching (ZVS) is achieved at the same time to reduce high switching loss caused by high switching frequency. Besides, planar transformer is used with the advantages of low profile and good thermal characteristic. Optimization design process is also proposed for lower leakage inductance to reduce the oscillation of switch voltage. Meanwhile, winding loss is also considered in order to obtain high efficiency. A 500kHz 36W prototype has been designed to demonstrate theoretical analysis. Obtained efficiency was up to 91.5% at full load.