Abstract: The application of hydraulic blasting technology in tunnel engineering has reduced the blasting dust con? centration to a certain extent and improved the working environment. However, due to high surface tension of water and its poor wetting ability to dust, the actual dust-suppressing effect is not ideal. In order to solve the problem of poor dust-suppressing effect of hydraulic blasting, a certain amount of surfactant and inorganic salt are added to the water, according to the characteristics of tunnel blasting dust, to reduce the dust generated by blasting. With experimental indicators of surface tension and wetting height, the best surfactant, inorganic salt synergist and their concentrations are determined by comparative experiment. The results show that the dust suppressant composed of surfactants and inorganic salts could significantly improve the wetting ability of the solution to dust; the dust suppressant composed of rapid penetrant T, CAB-35 and sodium silicate (with mass fractions of 0.20%, 0.30% and 0.10%, respectively) has good surface activity and wettability. Therefore, the dust suppressant could effectively reduce the concentration of blasting dust to improve the construction environment thereby.