Abstract: Polylactic acid (PLA) has promising applications in the field of air filtration due to its biodegradability. However, its low electrical activity and susceptibility to high humidity environments lead to insufficient filtration efficiency. To address this issue, structured and ultra-small-sized (~500 nm) metal-organic framework MOF-5 was synthesized using microwave-assisted methods. Subsequently, different loading amounts of MOF-5 were anchored onto the surface of PLA fibers through electrospinning-spraying technology (PLA/MOF). At a loading amount of 8wt%, the dielectric constant and surface potential were 2.3 times and 3 times higher than those of Pure PLA nanofiber membranes, respectively. The electrical activity of PLA/MOF nanofiber membranes was significantly enhanced, with a frictional electricity output voltage of up to 65.8 V. Compared to Pure PLA nanofiber membranes, PLA/MOF nanofiber membranes exhibited a greatly improved filtration efficiency for PM_0.3, both exceeding 96%. In a high-humidity environment (RH=90%) with an air flow rate of 85 L/min, the filtration efficiency of PLA/MOF nanofiber membranes with 8wt% loading could also reach over 90%. This MOF-functionalized nanofiber membrane, which enhances the electrical activity of PLA, holds great potential for applications in the field of human respiratory safety, especially in filtering out PM_0.3 in high-humidity environments.