Abstract: The phenomenon that fractional order is implied in many electrical engineering devices and system can be well described by fractional calculus. Equation solution is key to fractional circuit,but it is very difficult for existing methods to solve circuit equations with multiple fractional powers. This paper refined the traditional Laplace transform,and proposed a new method for fractional circuits—W transform,which is applied to solve the fractional circuits with rational powers. According to the characteristics of rational image functions in W domain,part of its fraction expansion method is given,which simplifies the equation of time-domain solution. Finally,examples are given to verify the correctness and feasibility of W transform.