A polymer, a composition, and a polysiloxane-polyimide material thereof are provided. The polymer includes a first repeat unit and a second repeat unit. The first repeat unit has a structure represented by Formula (I) and the second repeat unit has a structure represented by Formula (II) wherein A1 and A3 are independently tetravalent moiety; A2 is a divalent moiety; n≥1; m≥1; R1 is independently hydrogen, C1-8 alkyl, C1-8 fluoroalkyl, C1-8 alkoxy, or C6-12 aryl; and R2 is independently hydrogen, C1-8 alkyl, C1-8 fluoroalkyl, C1-8 alkoxy, C6-12 aryl, or a reactive functional group.