Abstract: In order to solve the problem that it is difficult to realize the simulation of fractional-order inductors and capacitors in resonant wireless power transfer system, the equivalent impedance is adopted to realize the equivalent of fractional-order capacitors. Based on the impedance characteristics of fractional-order capacitance, a fractional-order RLC_α series resonant bidirectional wireless power transfer (BD-WPT)system is presented. The circuit model of series resonant bidirectional wireless power transfer system with fractional-order capacitance is established. Furthermore, the relation between transmission power and efficiency is deduced and verified by simulation. The results show that compared with the integer-order series resonant system, the output power of the system is increased by 7.82%, and the transmission efficiency is increased by 0.58 percentage points.