Drum machine is a typical machine in modular machine tools or special machine tools. It's suitable for machining large quantities of parts. Drum is an important component in this kind of machine tools. The design process for a kind of hydraulic clamping distributor for a drum was analyzed, including the choice of oil path, the structure design of clamping distributor, parts materials selection etc. At last, a suitable hydraulic clamping distributor structure for the drum machine was carried out.