A fixed magnetic gap permanent magnet speed governor, including a cylindrical conductor rotor and a permanent magnet rotor disposed therein, the permanent magnet rotor includes at least one permanent magnet, two length sides of the permanent magnet are an N pole and an S pole respectively, two magnetic pole end surfaces and two length sides of the permanent magnet are arranged with fixed magnetizers and movable magnetizers respectively, the fixed magnetizers and the movable magnetizers form a closed magnetic loop. Adopting the fixed magnet gap structure improves an engagement area of speed governor and reduces assembling difficulty, saves a rare-earth material, increases a torque transmission capability. The adoption of a magnetic circuit adjustment structure reduces the power consumption of an adjustment execution mechanism, maximally reduces the size of the adjustment execution mechanism, reduces the overall size of the speed governor, reducing material consumption, saving installation space, and facilitating on-site installation.