The invention discloses a protective sleeve for fiber grating strain sensors, which comprises an outer shell. The cavity of the outer shell is movably connected with an inner shell. The front surfaceof the outer shell is fixedly connected with a fixed block. The front surface of the inner shell is fixedly connected with a locking block. The top and bottom of the cavity of the outer shell are fixedly connected with rotating shafts. Rotating shaft slots are respectively arranged in the top and bottom of the inner shell. The rotating shafts are matched with the rotating shaft slots. Through thecooperative use of the rotating shafts, a moving block, a first wedge block, a moving rod, a shifting block, a spring, a moving plate, a second wedge block, an inserting block, a sliding block, a movable hole, a movable frame and a clamping block, the problem that the existing protective sleeve is inconvenient to use is solved, users can replace a fiber grating strain sensor more conveniently, users can use the protective sleeve conveniently, and the practicability of the protective sleeve for fiber grating strain sensors is greatly improved.