Liquid phase diffusion bonding between ODS steel and pure W was carried out and its joint strength was investigated for fusion applications. A block of high-Cr ODS ferritic steel and a W plate were diffusion bonded at 1240 °C for 1h with/without an insert material under an uni-axial compression load and a high vacuum atmosphere. Cross sectional microstructures of joint region were observed by scanning electron microscope and the mechanical properties of the joint region were evaluated by hardness test and torsion tests. Microstructure analysis revealed that high Cr ODS ferritic steel block and W plate with insert material was successfully diffusion bonded with free of voids. Shear strength of liquid phase diffusion bonded ODS steel and W was higher than that of directly solid state diffusion bonded ODS steel and W. This was attributed to residual strain which is resulted from the difference of thermal conductivity between the ODS steel and W.