Abstract: The reflectors and thermal insulators of the high-temperature gas-cooled reactor (HTGR) are mainly composed of a large number of graphite and carbon bricks. Under seismic or impact loads, slips and collisions may occur between these components, which affect the structural integrity. The simplified numerical analysis model is an important method to study the dynamic behaviors of the multi-body structures. The parameters of the nonlinear joint elements used to simulate the collisions are crucial to the convergence and the accuracy of the analysis. In the present paper, three typical collision types of graphite components in HTGR were tested. The relationship between collision time and restitution coefficient in various collision types were measured. To study the difference of the boundary conditions between the test and the actual situation in the reactor, the commercial finite element analysis software ABAQUS was used to numerically analyze the different collision types to obtain more accurate collision characteristics. The experimental and numerical results were analyzed by the modified Hertz model. The equivalent stiffness and damping coefficients of the nonlinear collision connectors were obtained. Moreover, the numerical analysis method was used to study the influence of the mass and gap size of the internal component on the stiffness and damping coefficients of the Hertz model, which will provide a reference for the design and optimization of the graphite and carbon internal components of the HTGR.