Objective:To study charge storage stability of electret film made of polypropylene(PP)/porous polytetrafluoroethylene(PTFE)/polypropylene composite.Methods: The PP/porous PTFE/PP composite electret film was prepared with porous PTFE,polyethylene(PE) and PP by heat melting technique.The charge storage stability of the electret film and transportation were evaluated by using the methods of isothermal surface potential attenuation and open-circuit thermally stimulated discharge (TSD) current spectra.Results:(1) The charge storage stability of PP/porous PTFE/PP composite electret was superior to that of PP electret made under ordinary temperature,because the space charge of PP/porous PTFE/PP electret was transferred from deep trap to flat trap during the heat melting process.(2) Satisfactory charge storage stability was observed in PP/porous PTFE/PP electret when under the condition of high humidity.Conclusion:PP/porous PTFE/PP electret film has satisfactory charge storage stability and can be used as a novel enhancer in transdermal delivery of drugs.