Abstract: Effects of NaCl,CaCl_2 and FeCl_3 on turbidity of chitosan / pectin / Arabic gum PEC solution,swelling degree,contact Angle and mechanical performance of PEC membrane were studied.The effects of ions on the structures and properties of PEC membrane were investigated through infrared spectrum analysis and scanning electron microscope( SEM). The results showed that the turbidity of the PEC solution increased firstly and then decreased with increasing ion concentrations in the range of 0~60 mmol/L.Variety and concentration of ions had different influence on the swelling degree of PEC membrane.The membrane with 50 mmol/L FeCl_3 showed significant high swelling degree.Variety and concentration of ions also had diffrent influence on the Contact angle of the membrane. Ions addition can significantly improve the tensile strength of membrane and reduced the elongation rate at break of membrane,PEC membrane with 40 mmol/L FeCl_3 had the highest tensile strength..Infrared spectral analysis exhibited that ions had no influence on the complexation of chitosan,pectin,and Arabic gum.SEM photos showed that the PEC membrane with NaCl,and CaCl_2 had smooth surface,while the surface of membrane with FeCl_3 had concave and convex shape and was much coarser.