The special broaching machine for cylinder blocks is a special broaching machine mainly used for machining the joint surfaces between cylinder blocks and bearing caps. Aiming at the characteristics of large volume and heavy weight of the parts to be machined, this broaching machine is equipped with automatic loading and unloading devices so as to effectively reduce the labor intensity. This broaching machine is manufactured in horizontal structure, the positioning mode by two pins on one side plus floating auxiliary mechanism and hold-down during broaching guarantees the stability of accuracy. In the design of cutting tools, rough broaching and finish broaching are adopted, after rough broaching the recovery time of elastic deformation of the workpieces is held before finish broaching, which is beneficial to consistency of products. The broaching machine is equipped with airtight detection so as to protect safe operation of the broaching machine and safety of cutting tools effectively.