The air filter media were prepared using light polypropylene melt- blown nonwovens and then, corona charge was applied to achieve with low pressure drop and high filtration efficiency air filter. The processing variables for the corona treatments were set up, such as, the electric potential distance between the electrode and the nonwoven, the number of charging, the sequences of charging surfaces, and the concentration of ferro-dielectric nano particles. The electrical potential was applied in the range of 15 to 35 kV, the number of charging was 1 to 4 times with and without turn over the charging surface, the concentration of ferro-dielectric nano particle solutions were 0.5 to 1.5% (W/V). In this research, the most probable processing conditions gave a clue to make a HEPA filter when the media was plied 5 times. This HEPA filter showed its initial pressure drop be 7.7 mmAq and filtration efficiency be 99.99%.