Joining samples of carbon/carbon composites (C/C composites) and Ni based high temperature alloy (GH3128) were fabricated by vacuum hot pressing joining process with the powder of Ni and Si as the interlayer material. The effects of the joining temperature on the mechanical properties and microstructure of the joints between C/C composite and GH3128 were investigated by X-ray diffraction devices, scanning electron microscopes and universal material testing machines. The results show that with the joining temperature rising, not only does the element distribution in the joints become more uniform, but also the shear strength of the joining samples increases. When the joining temperature is 1160 oC, the shear strength of the joining samples reaches up to 12.6 MPa