This study numerically investigates the particle flow and deposition characteristics within array impingement cooling passage using the coupled computational fluid dynamics-discrete element method (CFD-DEM). The unsteady growth process of the particle deposition layer on the impingement target surface is captured, and the underlying mechanisms by which particle diameter and particle inlet volume fraction affect the flow and deposition behaviors are revealed. The results indicate that the interaction between adjacent impingement jets induces the formation of collision vortex structures. A conical deposition layer is gradually built up in the impingement stagnation region, whereas a band-shaped deposition layer is generated in the jet interaction region. Furthermore, both particle deposition mass and deposition rate increase with the increase of particle diameter and particle inlet volume fraction. Specifically, the increase in particle diameter enhances the particle inertial forces, exacerbating momentum dissipation after collisions, whereas the increase in particle inlet volume fraction leads to a higher probability of inter-particle collisions.