The utility model discloses a steam turbine stop valve overhauls uses locking device, including setting up the support frame on main valve support, set up in locking structure on the support frame, the locking structure includes first locking structure, first locking structure is including a limit structure of a pair of relative setting at least, a limit structure is butt in the first steam valve wall both sides of stop valve seat respectively, still include with first locking structure is the crisscross second locking structure that sets up each other, second locking structure includes at least one the 2nd limit structure, the 2nd limit structure all with the crisscross second steam valve wall one side butt of the first steam valve wall of stop valve seat. Limit main valve's displacement when main valve examines and repair, can not produce extra power and moment to device interface because of main valve's displacement when guaranteeing to examine and repair, satisfy the technical requirement of the unstressed installation of steam turbine factory.