In the manned spacecraft rescue at low altitude, the initial conditions of recovery system at parachute-opening point affect obviously cabin safety landing, such as its velocity, altitude and trajectory angle. Similar to the normal return rescue, the process of recovery system rescue at low altitude also has the stages of deployment, inflation, and full-inflation of multilevel parachute. Through applying the recovery system landing dynamic model, and analyzing contrastively the results from simulation, it can be known that the initial altitude from ground of recovery system at parachute-opening point is the first effect factor on the cabin safety landing in rescue at low altitude. In the end, the deceleration process of parachute-opening of multilevel parachute in recovery system is analyzed in detail.