Abstract: The ultrasonic spot welding (USW) of 1060 aluminum alloy and N4 nickel alloy dissimilar metals was studied, particularly the microstructure and mechanical properties of ultrasonic welded joints. Results show that 1060 aluminum alloy and N4 nickel alloy dissimilar metals can be successfully welded by using USW, the joint has high toughness and strength. The USW parameters for successfully joining of aluminum and nickel dissimilar metal were determined, i.e. the welding pressure and welding time were in the range of 25.2 MPa~36.0 MPa and 75 ms~85 ms, respectively. Shear strength of the joint welded at 85ms and 32.4 MPa was higher than that of the aluminum base metal. Furthermore, the XRD and EDS results show that only Al and Ni elements were found at the interface, forming a 2 μm diffusion layer, but no intermetallic compounds appeared.