Wind turbine gearbox below 1MW, mostly applies parallel shaft or planetary gearing transmission; using gears made of quality steel alloy, in which external gears reaching class 5 (ISO1328) in precision and internal gears class 6 (ISO1328); carrying out dynamic simulation analysis with on gears with simulation software to get best profile effect; conducting FEM analysis on housing, torsion arm, planet carrier to optimize the structure under the precondition of ensuring strength and stiffness; providing forced lubrication to bearings to prolong bearing service life.