Abstract: Through the analysis on structure of boring mold, in the paper puts forward design method of boring mold. The structure of boring mold、boring bars and boring tool is emphatically analyzed, in particular, boring mold positioning and clamping; Several typical positioning methods of the boring bar are expounded.; How to ensure the verticality the boring tool of vertical plane is demonstrated in detail. Through the above researchs, can improve boring accuracy of the machine head box or the feed box, the skew of the gear shaft can be avoided, the noise of gear mesh is reduced, it has practical application value.