The influence of primary aircraft-ramp parameters on ski-jump takeoff safety was analyzed by numerical simulation. The match set of primary parameters that satisfy the takeoff safety criteria was computed and the match law was summarized. The results indicate that the takeoff mass is the primary effect factor of flight path descent. Enhancing preset elevator angle and ramp angle can help to decrease the flight path descent. The preset elevator angle influences the attack angle. Too large preset elevator angle would lead to stall. The ramp angle influences the pitch rate, which attains its peak value when ramp angle is 12°. Within the boundary of the match set, the range confined by preset elevator angle and ramp exit angle decreases with the increase of takeoff mass.