To improve the drainage performance of iron tailings dams, permeability tests were conducted on geotextile filters in iron tailings dams under different vacuum negative pressures. The particle migration laws within the filter and the variation laws of the pore structure of the geotextiles were analyzed, and the influence of vacuum negative pressure on the permeability characteristics of the iron tailings-geotextile filter was investigated. The results indicate that vacuum negative pressure can significantly improve the permeability of the iron tailings-geotextile filter. Under stable seepage conditions, among the three types of geotextiles, staple fiber, namely filament and filter cloth geotextiles, the permeability coefficient of the filament geotextile filter is the highest, followed by that of the filter cloth geotextile filter, and the staple fiber geotextile filter exhibits the lowest permeability coefficient. The permeability coefficient of the staple fiber geotextile filter increases significantly starting from a vacuum negative pressure of 70 kPa and then increases with the increase of vacuum negative pressure. For the filament and filter cloth geotextile filters, the maximum permeability coefficients are obtained at a vacuum negative pressure of 70 kPa, increasing by 94.6 and 14.2 times, respectively, compared with the stable permeability coefficients without vacuum action. The improvement effect of vacuum action on the permeability characteristics of the geotextile filter is influenced by the fiber thickness and fabric thickness of the geotextiles. For geotextiles composed of coarser fibers or those with greater thickness, the improvement effect of vacuum action on the permeability characteristics of the filter is more pronounced.