As one of the eight mine systems,underground ventilation system is the top priority for safe production,while the selection of fans is the key point to determine whether the ventilation system operates smoothly.In view of the production features such as excessive underground goafs and concentrated layout of stopes and development projects in a lead-zinc mine in Gansu,the original ventilation system air inlet for two wings and air return for the center has shifted to air inlet for the center and air return for two wings central diagonal type ventilation system by design.Ventsim simulation software was used to establish a three-dimensional ventilation model,which calculated ventilation resistance of different periods based on different production levels and stopes,so as to provide an important theoretical basis for the selection of fans.