To represent a ballistic trajectory with B-spline,Monte Carlo method is used in the simulation of B-spline separating signals method.A suggestion is given on how to add external knots to the internal knots sequence.Consistency of B-spline approximation space is discussed to demonstrate the relevant theorem.Further more,B-spline separating signals method is validated by a comparison with Monte Carlo simulation.It decides efficiently exact knots sequence needed to represent a ballistic trajectory.With the knots sequence,the parameters to be estimated is greatly eliminated.