Aiming at the current situation that the full time coefficient of the cruciform parachute lacks value basis and the full time is not easy to estimate， this paper proposes the idea and method of calculating the full time coefficient of the cruciform parachute under the subsonic condition based on the measured value of a small sample size. With the help of LS-DYNA， the inflating process of the canopy is simulated and verified， and the rounding result of the full time coefficient of the cruciform parachute is obtained.