Abstract：Aiming at the problems of insufficient stability and low power generation efficiency of the existing

power supply means for offshore ocean observation equipment，and low power density of direct drive wave energy

power generation device due to the low running speed of ocean waves，it proposed to apply the magnetic lead screw （MLS）as a speed increasing device in the field of wave energy power generation，and based on its topology，the magnetic vector potential energy theory was introduced to establish a two-dimensional magnetic field analytical model，and the speed increasing operation mechanism of the magnetic lead screw was expounded. On this basis，the structure of surface-mounted magnetic lead screw was optimized and its thrust and torque performance was analyzed. Meanwhile，a magnetic lead screw composite generator was designed according to the optimization results，and the output power was compared with that of a cylindrical external permanent magnet linear generator under different wave speeds and load conditions. The simulation results show that the output power of the magnetic lead screw composite generator under the same volume was greatly improved compared with that of the cylindrical external permanent magnet linear generator in the low-speed wave motion condition，which is more suitable for the low-speed and large-thrust direct drive wave energy power generation field.

      Key words：direct drive type；wave energy converter；magnetic lead screw（MLS）