Continuous rotary friction welding was used to aluminum and steel dissimilar metal joint. Microstructure and property was analyzed by SEM and EDS. The test results show that the aluminum-steel friction welded joint is tightly bonded and the interface is corrugated under the conditions of the rotation rate of 700 r/min,the upsetting pressure of 4.5 MPa,and the upsetting time of 2 s. The tensile strength of the joint is up to 210 MP,and the tensile fracture occurs on the aluminum side. The intermetallic compound layer with a thickness of less than 2 μm is formed by the diffusion of elements on both sides of the bonding interface of the aluminum steel dissimilar material joint. The microhardness changes step by step at the interface,and the hardness at the interface of forming intermetallic compounds is up to 230 HV.