The invention relates to the technical field of casting, and discloses an assembling core mould. The assembling core mould comprises a main body framework, an underframe and an end core stop block, wherein the underframe is positioned on a side part of the main body framework and can be moved in a length direction or a width direction of the main body framework; and the end core stop block is arranged on the underframe and can be inserted into sunken parts of the bottom parts of sand cores. According to the assembling core mould provided by the invention, through arrangement of the main body framework and the movable underframe, the length of the assembling core mould can be lengthened or shortened according to requirements, so that production of assembling cores of different lengths can be met. In addition, the end core stop block can be inserted into the sunken parts of the bottom parts of the sand cores; in order to meet a design requirement of a part of machine types, a front end core and a rear end core can be necessarily moved outwards to conveniently assemble water jacket cores, tappet rod cores or upper cover cores and the like, the end core stop block is protruded and is inserted into the sunken parts of the corresponding sand cores to prevent the sand cores from being dumped during movement.