Abstract: The scattering of relativistic particle is discussed. The Lorentz factor formula of scattered particle is found. The results show that the collision rule of high energy particles is the same as the one of low energy particles if the masses of two rest particles are the same; the velocities of colliding particles are interchanged in collinear collision. If the masses of two rest particles are different, the collision rule of high energy particles differs from the one of low energy particles, the mostly energies of heavy-particle loss in collinear collision, and the velocity of light- particle is equal approximately to the one of light, but is not equal to two times velocity of heavy-particle.

Key words: relativistic particles, scattering, Lorentz factor