A copolymer according to the present disclosure is provided, which includes 30 to 80 mol % of a repeating unit represented by formula (I), 5 to 25 mol % of a repeating unit represented by formula (II), and 5 to 30 mol % of a repeating unit represented by formula (III): wherein R1 is C6-C13 aryl group, C7-C13 aralkyl group, C6-C8 halogenated aryl group or C7-C8 aryloxyalkyl group; R3 is C3-C16 alkyl group or C3-C6 alkoxy substituted alkyl group; R5 is a single bond or C1-C3 alkylene group, R6 and R7 are independently C1-C3 alkoxy group, R8 is polysiloxane with methyl and phenyl groups; and R2, R4 and R9 are independently hydrogen or methyl. In addition, a resin composition, a packaging film and a package structure including the same are provided.