Mortar mixer is widely used in the construction of Metro works, however, it has such problems as mortar leakage and maintenance inconvenience. The design and manufacturing of the mixing system of the mortar mixer are optimized and key parts to be used for the mixing system of the mortar mixer are proposed. In the end, the mortar leakage of the mortar mixer is mitigated and the service life of the mixing system of the mortar mixer is prolonged. 