By using N-S equations, RNG κ-ε model and discrete phase model of Euler-Lagrange method, numerical simulations on the removal trajectories of contaminant particles of different sizes and types on the mirror surface are conducted with the commercial software Fluent. Benefiting from the simulation results, a useful device which can capture and collect debris from the mirror surface online is built. Ultimately the efficiency of cleaning and cleanliness of transport mirrors are improved. And to some extent, the chances that contaminant particles go into the surrounding environment and further pollute other optical components are reduced.