The Ni coating of 10 μm in thickness was firstly deposited on the cylinder surface of pure tungsten by electrochemical deposition, and then the W/steel joint cylinders were prepared by the hot isostatic pressing (HIP) diffusion bonding process for nuclear component application. The HIP bonding parameters were set as 900 °C/100 MPa/1 h. The structure and composition analyses show that the metallurgical bonds are achieved with a tensile strength of about 236 MPa. However, the W/steel joint fractures at W substrate near the bonding interface due to the residual stress concentration. The Cu addition was used as the soft intermediate layer to release the residual stress by creep or yield mechanism, thereby improving the tensile strength of W/steel joint to about 312 MPa. The adhesive force of coating and the hardness distribution in the bonding interfaces were also discussed.