Abstract: Water injection into coal is a good method for reducing dust in mining face.Based on geological characteristic of 4-1 Mining Face at-140m level in Changyugou Colliery,this paper researched water injection manner and parameters.It built up a seepage dynamic model of water injection in long holes by applying multi-physics coupling simulation software-COMSOL and numerically simulated infiltration radius of injecting water under different working conditions.Results showed that this design of water injection was feasible and effective.