Abstract: Aiming at the difficulty in forming an effective bonding for the AZ31B/CF-PA66 heterogeneous joints, the ultrasonic assisted hot press welding was adopted to join AZ31B and CF-PA66, aiming to enhance the joining performance of the heterogeneous joint by regulating the mechanical interlocking and chemical bonding effects at the interface. Firstly, Abaqus software was used to introduce viscoelastic heat generation model to analyze the interface temperature rise caused by the ultrasonic field, thereby determining the influence law of welding pressure on the temperature field. Secondly, a micro-nano oxide layer was prepared on the surface of AZ31B via anodization process, which could enhance the mechanical interlocking and chemical bonding capabilities of the magnesium alloy surface. Finally, process experiments were conducted using ultrasonic assisted hot press welding. The results show that the joint exhibits optimal performance under the initial temperature of 280 ℃, welding pressure of 0.2 MPa and welding time of 10 s, with a shear strength reaching 32.23 MPa.