The collinear collision dynamics of the three ball chain is able to demonstrate one of the difficulties of the problem of collisions of multi body system:non unique solution.The paper presents three ball chain collision is modeled by Hertz contact, numerical algorithm is found to solve the contact model, the finite element model is used to verified it.Research shows:compared with linear model, the contact forces between three balls by Hertz model are closer to the finite element results;based on the Hertz model,the change of the contact forces is analyzed during the collision process;it is researched that the stiffness ratio and mass ratio affect the state of motion of each ball after the collision,and study the established condition of two girid body models collision orders.