Gear pump is depend on the seal on a shell in two or more than two gears, produced in the process of mutual engagement of the workspace volume change to transport liquid pump. Gear pump in the engine lubrication oil pump, are mostly produced by small and medium-sized enterprises at present. Shell to improve the machining precision of the operations, how to further improve the quality of production, reduce the energy consumption in the production process, improve production automation, is the eternal subject of housing studies.Gear rotatable housings, basic pieces of artillery in the balance beam. It will balance beam, shaft, bearings, sleeve and gear parts assembly by mutual positional relationship as a whole, according to a predetermined rotation relation to coordinate theirmovement. Therefore, the processing quality of the housing not only affects the precision of assembly precision and movement, and the impact of artillery movement balance performance and life.