Abstract Calculate in design which cuts the cutting department of main introduction mining machine of this manual.It is made up of a gearbox and moderate breeze gear wheel transmission that the advanced mining machine cuts the cutting department,cut the electrical machinery of cutting department and put to fix up horizontally in the rocker arm,the power that the motor outputs leans on around of transmission of department of gear wheel and planet round via the tertiary straight tooth ,urge the cylinder ti rotate finally.Cut the cutting department and adopt the floating structure of four planetary forms,have reduced the physical dimension, adopt the large angle to curve the rocker arm to design,have strengthened the space of coal,have improved the coal result of putting. Key words: Mining machine;Cut the cutting department;Gearbox;A department of planet;Desigh