The invention relates to a lower case body embedded lump for an engine crankcase. The upper part of the embedded lump is provided with a mounting hole seat of a crankshaft main journal, the side edge of the embedded lump is provided with dentiform bulge structure, and the lower part of the embedded lump is provided with a main bearing cover bolt installation lug. The improvement of the embedded lump is characterized in that an aluminum alloy containing hole is arranged between the mounting hole seat of the crankshaft main journal and the main bearing cover bolt installation lug. As the aluminum alloy containing hole is additionally arranged on the embedded lump, not only convex teeth but also aluminum alloys in the aluminum alloy containing hole are arranged between the lower case body aluminum alloy and the embedded lump to prevent the embedded lump from moving up and down. Thus, compared with a common embedded lump, the embedded lump has larger limitation area and bonding force, andthe lower case body embedded lump for the crankcase and the lower case body are not easy to be loosened in the processes of starting and running.