A numerical model of laser irradiating metal under airflow is established. The flame ablations irradiated by laser under different airflow velocity and thickness of tin plates are simulated by the CFD software and contrasted with experimental results. Laser irradiation on metal plates with different thickness affected by airflow velocity is analyzed based on the research on liquid metal removal and heat convection mechanisms. The results indicate that the melting-through time of thicker metal plate decreases with the increasing airflow velocity as deeper craters are formed in the irradiation process and the melted liquid metal is more difficult to remove at the same airflow velocity; however, the melting-through time of thinner metal plate increases with the increasing airflow velocity as the craters are shallower, the liquid metal is easier to remove, and the heat convection is enhanced by mixing of the removed metal drop with air.