For the requirements of drilling and threading in plumbing and sanitary products, the whole scheme of drilling and tapping combined machine tool was designed based on the secondary development platform of standard HNC8, and a method to realize the manual teach-in function using user macro programs and G codes was proposed, which could ensure the relationship between the synchronous axial feed and spindle rotation angle under rigid tapping; HNC8 was used to configure dual-channel parameters and to develop interactive interface so as to realize dual-channel parallel machining of modular machine tools. The results show that the machine tool is easy to operate, with high machining accuracy and high production efficiency.