As the population of the world's major cities increases, urban ground transportation capability reaches its limits. Consequently, electric vertical takeoff and landing aircraft have been developed to address this issue. Modern vertical takeoff and landing designs vary in configurations, each possessing distinct aerodynamic properties. In this work, we focus on the interaction between rotors and fixed wings in a parallel layout, using a prototype with an unconventional configuration as an example. The interaction between the slipstream of rotors and the wake of fixed wings is analyzed using the vortex particle method. Actuator surface model is used to deal with the boundary problem between the wing and the rotors. The applicability of the simulation method adopted in this paper is verified through experimental tests on the thrust and torque of the rotors. The results indicate that under the condition of forward flight at zero angle of attack, the existence of rotor slipstream induces a significant increase by three to four times the local lift on the wing. Correspondingly, under vertical takeoff and hovering conditions, the existence of the rotor slipstream causes the local effective velocity and circulation of the wing to increase. On the other hand, at zero angle of attack and a forward flight, the lift coefficient of the rear rotors increases slightly due to the presence of the wing wake. The lift distribution of the rear rotors along the radial direction also changes greatly.