In order to improve the spray dust efficiency of a gas-water nozzle in the coal mine workplaces with high concentration of dust, the gas-water nozzle atomization characteristic parameters were studied through experiments, and the changing rule between the droplet average diameter and the gas/water flow was obtained; this paper studied the dust removal process of the gas-water spraying in the comprehensive tunneling face. The corresponding mathematical model was established and the expression of the gas-water nozzle's efficiency was provided. The curve of dust removal efficiency was drawn by use of Matlab. Research results show that: when the water flow remains constant, the dust removal efficiency increases with the increase of the gas flow; when the gas flow remains constant, the dust removal efficiency increases firstly and then decreases with the increase of the water flow; the larger the dust size is and the longer the effective distance of spray droplets is, the easier the dust settling is. Only when the gas flow is greater than 150×10^-5 m³/s, the dust reducing efficiency can reach 80%, and the best gas water flow ratio lies between 100 and 150. Based on the size distribution and removal requirement of dust in working face, choose the best gas/water flow can be chosen by reference to the related curve so that better dust removal effect and economic benefits can be achieved.