Abstract: Be aimed at improving the efficiency of injector in mine automatic drainage system, the influence of control- valve on the process of injector vacuum- pu mping was analyzed. Using the common DN25 mm injector which nozzle diameter was 8 mm as an example, the hydrodynamics software FLUENT was used to carry ou t simulation of internal flow field of injector with the different flow area of the control valve, and some experiments were done. From the analysis results, a conclusion co uld be got, when the control valve path area and nozzle path area ratio greater than 1. 5, vacuum pressure values for a longer time could be established; when the area ratio greater than 2, it would have a shorter time. This conclusion provides theory basis for the design of the control valve in the future.