Abstract: Potato starch as base material,chitosan and nano TiO₂ as enhancement phase,potato starch film(P),potato starch/chitosan composite film(P+Ch),potato starch/nano TiO₂ composite film(P+TiO₂),potato starch/chitosan/nano TiO₂ composite film(P+Ch+TiO₂)were prepared with enhancement phase of chitosan and nane Tio₂. Tomatoes and green peppers were coated,and then it was measured by the weightlessness rate,soluble sugar and titratable acid content during the storage. Freshing effect of composite coating on tomatoes and green peppers,and comparative analysis four groups of composite membrane performance and preservation of tomatoes and green peppers were evaluated. The results showed that,chitosan,nano TiO₂ and potato starch were compatible. The mechanical strength of P+Ch+TiO₂ was improved by 91.13%,77.78% and 84.82%,respectively,compared with that of P,P+Ch and P+TiO₂. The hygroscopicity decreased by 60.91%,6.76% and 49.45%,respectively. After stored at room temperature 15℃ for 30 d,the weight loss rate of cherry tomatoes and green pepper were lower than those of the control group,and the contents of soluble sugar and titratable acid higher than those of the control group. To summarize,the addition of chitosan and nano TiO₂ improved the properties of the starch composite membrane. And the composite membrane solution had a very good preservation effect on cherry tomatoes and green pepper.