The utility model provides an engine cylinder head bolt tightening mechanism comprising ten tightening shafts, a tightening shaft mounting base plate and a mounting bracket, the ten tightening shafts are arranged on the tightening shaft mounting base plate, each tightening shaft is correspondingly provided with a self mounting assembly, wherein the mounting assembly comprises a displacement cylinder, a tightening shaft mounting plate, a linear guide rail and a sliding block, and the engine cylinder head bolt tightening mechanism is characterized in that the displacement cylinder and the linear guide rail are arranged on the same line, the linear guide rail is arranged on the sliding block, the tightening shafts are arranged on the tightening shaft mounting base plate in single layer form. The tightening shaft mounting plate is provided with an arc slot. The opposite sides of the tightening shaft mounting base plate are respectively provided with an adjusting block A, an adjusting block B and an adjusting block C. The double-layer arrangement structure of the existing tightening mechanism is changed into the one-layer structure, so that the structure is simple, the appearance is compact, the operation is convenient, and the practical applicability is high.