The invention relates to an aligning device, in particular to an aligning device used for lathe machining of the guide vanes of a gas turbine. The invention aims to solve the problem that at present,when guide vanes are aligned, every guide vane needs to be aligned by using a dial indicator, which is time-consuming and laborious. An aligning device used for lathe machining of the guide vanes of agas turbine comprises a positioning block, an adjusting block and a machine-tool connecting block, wherein the positioning block, the adjusting block and the machine-tool connecting block are connected end to end sequentially and detachably. The invention belongs to the technical field of gas turbines.