Under strong impact loading, metal materials will produce deformation and show ejecta behaviors. The mixing phenomenon, due to the detached matters entering into the background fluid, has a direct influence on the compression properties. According to the researches of ejecta, the damage and mixing are closely related with the loading state and the dynamic process. Up to now, many results have already been obtained under the condition of the directive impact of detonation. Further study on the metal materials response driven by detonation collision is needed. Previous studies have focused on the macro characteristics, such as the collision uplift and destruction. In this paper, we aim at the wave system's interaction process, in order to obtain the physical detail and to reveal the mechanisms of dynamic behaviors in the collision region. Investigations are carried out by means of both the numerical simulation and the shock polar theory analysis. Planer tin flying layer calculation model is designed for numerical simulation, so the sliding wave systems and shock conditions are obtained effectively. Based on the numerical results in the plane tin flying layer, the shock polar theory forecasts that the Mach reflection will occur, and the images of wave interactions given by numerical simulation also display the three-wave structure, which is the typical structure of the Mach reflection. Quantitative comparisons between the numerical results and theoretical analysis of the shock polar are in good agreement with each other. Furthermore, the critical conditions of Mach reflection in the cases of different shock conditions are given. Meanwhile typical characteristics of the histories of free surface velocity in the collision zone are analyzed. From the numerical and theoretical analyses, the shock dynamical model in the collision zone is proposed to reveal the mechanisms, and the model is very important for investigating the collision zone problem deeply in decomposition way. The results illustrate that in the collision zone there exist multiple kinds of shock loading ways, including one-dimensional once plane impact region, two-dimensional once oblique impact region, and two-dimensional twice oblique impacts region. The complex loading dynamic processes coupling with the unsteady flow field lead to the distributions of the peak pressure at different positions in the collision zone. The corresponding destroyed behaviors are shown, and thus we can establish the relationship between the reflection wave structure and the fracture morphology of the collision zone. This research results will provide an important theoretical support for the understanding and interpretation of the physical phenomena of material deformation, damage and mixing in the collision zone.