The invention relates to the field of crude oil recovery, and discloses a polymer having a surface activity function, and a preparation method and application thereof. The polymer contains a structural unit A, a structural unit B and a structural unit C, wherein the structural unit A is a structural unit having a structure shown in Formula (1); the structural unit B is a structural unit having a structure shown in Formula (2); and the structural unit C is a structural unit having a structure shown in Formula (3). According to the invention, a polymerizable monomer having surface activity is introduced onto a macromolecular chain, and the ether chain structure determines that the synthesized copolymer has high hydrolysis resistance and thermal stability, thereby improving the aging resistance of the polymer; and meanwhile, the surface tension and interfacial tension of the polymer solution are greatly reduced, so that the polymer has favorable surface activity and fine compatibilization, emulsification and oil washing capabilities, thereby improving the crude oil recovery factor. The Formula (1), the Formula (2) and the Formula (3) are shown in the specification.