Abstract: The effects of different component, propionic acid, ethanol and n - butanol as cosurfactant, calcium chloride as salt, on the phase behavior of the food - grade microemulsions were studied in this paper. Simultaneously, the determinations of particle size distribution were also carried out. The propionic acid as cosurfactant did the best solubilizing effect.Microemulsions, which was formatted by propionic acid, was very small ( 10nm) in its particle size.In addition, as the concentration of CaCl2 increased, the ability of solubilizing effect declined.In the last period of the study, fresh- cut grapes were dipped in the microemulsions systems for 1min, which contained 0.3, 0.4, 0.5g /kg CaCl 2 , respectively. Results showed that the microemulsions could delay the grape soften and inhibit grey mold.In addition, the group of 0.3g /kg had the best inhibition effects.