The load reduction technology of the whole aircraft parachute aims to reduce the opening shock by use of the slider at the skirt of the parachute, which controls the deployment of the parachute under the influence of the aerodynamic force. The influence of the design parameters of the slider on the load reduction effect has always been a difficult problem during the development of the whole aircraft recovery parachute. In this paper, GRS6 650SD parachute slider is taken as the research subject. By analyzing the operating principles of slider, the factors that affect the load-reducing effect of slider are found. The LS-DYNA fluid–structure coupling method is used to simulate the reefing and opening process of the whole aircraft parachute with different slider reefing ratio and fabric porosity. The simulation and airdrop test have demonstrated the influence of the design parameters of different slider structure on the slider movement law and load-reducing effect, so as to provide reference for the design of the slider of the whole aircraft parachute.