The invention relates to a positioning and clamping mechanism for a plurality of drill holes. A clamp body is matched and locked with a T-shaped groove in a machine table through a second positioning key; a cushion plate is matched and locked with a positioning groove on the clamp body through a third positioning key; a fixing V-shaped block is matched and locked with the positioning groove on the clamp body through a first positioning key; a plurality of V-shaped grooves on the fixing V-shaped block is used for placing workpieces to be machined; a plurality of supporting bodies are arranged side by side and corresponding to a plurality of V-shaped grooves on the fixing V-shaped block, the supporting bodies are respectively locked on the cushion plate, a slideable pushing plate is installed in each supporting body respectively; the front end of the pushing plate is hinged with a compressing plate through a columnar pin, a compressing bolt is installed in the supporting body; the front end of the compressing bolt is connected with the pushing plate, the rear end of the compressing bolt is equipped with a handle; a rotating handle can drive the compressing bolt to drive the pushing plate to glide in the supporting body forwards; the workpiece to be machined is completely compressed in the fixing V-shaped block. The positioning and clamping mechanism is simple and practical in structure, flexible in operation and good in interchangeability.