The present invention relates to the technical field of design and manufacture of magnetic couplings and provides a self-alignment protection device for permanent-magnet coupling, the self-alignment protection device comprises a first rotor and a second rotor respectively in fixedly connection with a load shaft (8) and a driving shaft (9), the first rotor and the second rotor being respectively mounted with permanent magnets that are mutually coupled to transmit torque, the first rotor and the second rotor are respectively configured with an inner conical surface and an outer conical surface that are coaxial and have mutually matching tapers, the self-alignment protection device further comprises an axial adjustment mechanism for adjusting the relative axial position between the first rotor and the second rotor. This technical solution solves the technical problem that the existing magnetic couplings are inconvenient to install and adjust.