The Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti17) titanium alloy is the main material used in manufacturing blades and disks of aero engines, and it is always jointed with different microstructures for the design constraints. In this work, the residual stresses of linear friction welding of beta Ti17 and alpha + beta Ti17 are measured by contour method and the X-ray diffraction method. The welding-induced tensions were found to be greater on the beta side than that on the alpha + beta side, and had an obvious reduction in the weld centre. After the post weld heat treatment (PWHT) of 630 degrees C for 3 h, all tensions on the beta side relax to a very limited value while some new PWHT-induced compressions are found on the alpha + beta side.