At present, the plastic tarpaulin used in soil fumigation process has been proved to be able to penetrate into the fumigation steam and cause obvious loss to the atmosphere. New low permeability membranes are being developed to reduce fumigant emissions and improve efficacy. A fast, reliable and sensitive method is needed to measure the permeability of various membranes that may be used in new management practices. Filmpc provides a method for estimating the mass transfer coefficient (H) of fumigants in agricultural films. H is a measure of diffusion resistance. Unlike other permeability measurement methods, h is an attribute of film chemical combination, independent of the concentration gradient of the whole film. The model relies on a mass balance method, and adsorption and diffusion are carried out on the membrane. The results show that this method produces a sensitive and reproducible method for measuring membrane permeability.