Abstract: In order to study the influence of water quantity change in water supply network on underground working face water pressure, and find the approximate range of water pressure change so as to take measures before the water pressure drops to the normal water supply critical point, based on the theory of abnormal similarity and the experimental site, we deduced the similarity criterion number of dustproof water supply pipe network; on this account, we set up a similar experimental model and verified by experimental data. And then on this model, we study the correlation of water volume and pressure through the experiment, and use the function fitting method to carry out fitting for the experimental results. The results show that the more the pipe section shared with the selected working face, the greater the influence of the change of water quantity on the water pressure of the working face.