The invention discloses a submersible direct-drive permanent magnet synchronous motor, comprising a shell and at least two permanent magnet motors, wherein each permanent magnet motor is provided with stators and a rotor; coil windings are arranged in slots of the stators; and permanent magnets are uniformly arranged on the cylindrical surfaces of the rotors. The motor is characterized in that all the permanent magnet motors are fixed in the shell; the same phase coil windings of the permanent magnet motors are serially connected together; and rotor shafts of the adjacent permanent magnet motors are fixedly connected by coaxial connectors. The diameter of the shell is phi89-150mm and the length of the shell is 2-12m. The rotating speed of the permanent magnet motors is 0-300r/min. The motor solves the problem of synchronization of a plurality of motors and has the advantages of low rotating speed and high starting torque. The motor has slender overall structure, forms down-hole drive after being placed underground, dispenses with sucker rods when being connected with the screw pumps, dispenses with the mechanical reduction device, improves the system efficiency, reduces the energyconsumption and saves the production cost.