The invention provides an adjuster for adjusting the roof of a sail house, which comprises a fixed part which is fixedly arranged relative to the sail house and a movable part, wherein the movable part is provided with an adjusting part to form into a first motion direction and a second motion direction which can be self locked and adjusted relative to the fixed part and a lug boss or U cup-shaped tightening part which is contacted with a pull rod of the flexible roof; the fixed part is a fixed block with inner screw thread; the movable part is a rod with external screw thread; and the inner or external adjusting part arranged at the movable part realizes the screw thread motion connection between the fixed part and the movable part, thereby tensioning and loosening the flexible roof. Theadjuster has simple structure, low cost, simple and reliable operation and small use amount, only can be installed at the corner or the middle of the sail house, and can smoothly tension and loose the sail house with the flexible roof, thereby leading the sail house to have technical effects of beautiful appearance, safety and durability, etc.