To study the unsteady effects of rotorcraft on the aerodynamic performance of parachute, a numerical simulation method for the unsteady compound flowfield of rotorcraft-parachute system was established. First, the pressure implicit split operator (PISO) algorithm and Reliazable k-ε model were applied to improve the efficiency of transient calculation and the accuracy of viscosity calculation, and the detail changes in the wake vortex were accurately captured. Subsequently, an efficient dynamic mesh updating model was established, and the Diffusion Smoothing and Remeshing methods were adopted to classify meshes with different deformation scales. Then, the unsteady wake characteristics of the rotorcraft-parachute system and the aerodynamic characteristics of the parachute were studied. Results show that the rotor increased the length of the frontal wake area. The influences of the wake on the parachute were increasing, and the flowfield structure at the entrance of the parachute was asymmetrically distributed. The negative vorticity area at the tail of the rotorcraft gradually moved up and connected with the negative vorticity area at the entrance of the canopy, which promoted the separation of the vorticity from the canopy. The number of vortices in the wake increased significantly. On the other hand, the rotor disrupted the vortex distribution around the rotorcraft, which formed a rotating vortex region. The range of shedding vortex in the wake became smaller. The vorticity magnitude entering the canopy was weakened due to the vorticity viscous dissipation. With increasing rotor speed, the outer pressure of canopy remained the same, but the inner pressure and pressure coefficient gradually decreased, and the pressure difference was reduced, so the average drag coefficient of the parachute gradually decreased.