A bionic arm comprises a bionic palm and at least one finger. The at least one finger comprises a nanofiber actuator. A nanofiber actuator comprises a composite structure and a vanadium dioxide layer. The composite structure comprises a carbon nanotube wire and an aluminum oxide layer. The aluminum oxide layer is coated on a surface of the carbon nanotube wire, and the aluminum oxide layer and the carbon nanotube wire are located coaxially with each other. The vanadium dioxide layer is coated on a surface of the composite structure, and the vanadium dioxide layer and the composite structure are located non-coaxially with each other.