Abstract: The work efficiency and work safety of shearer have been focused for design researchers because of the bad and complicated geological conditions in coal mining working face. The design of transmission system are conducted based on the transmission characteristics analysis of MG500/1180-WD electric haulage shearer's ranging arm. The genetic algorithm is utilized to optimize the volume of the gears in transmission system. The volume of optimized gear reduces obviously and most of the gear volume reduces over 8%, which shows that the optimization effect is remarkable.The vibration characteristic curve and statistics of transmission system before and after optimization are obtained through the no-load vibration test, and it is concluded that the vibration amplitude of shear's ranging arm after optimization is less than that of before optimization, which verified the correctness of the genetic optimization results.