The utility model discloses a lower crankcase of engine, form the interior pot shell in machine oil groove including the lower part, still wrap up in the outer pot shell of interior pot shell periphery, be provided with the heat transfer passageway that supplies the heat transferring medium to pass through between interior pot shell and the outer pot shell, heat transfer passageway intercommunication heat transferring medium entry and heat transferring medium export. This kind of technical scheme divides into interior pot shell and outer pot shell bilayer structure with the outside casing in machine oil groove of lower crankcase lower part, set up the heat transfer passageway in the intermediate layer of the two, this kind of design makes integrative setting of the direct interior pot shell with the machine oil groove of heat transfer passageway in other words, make the heat transferring medium directly touch with the inside groove shell joint, the heat can conduct between heat transferring medium and machine oil through heat transfer passageway and interior pot shell more high -efficiently, the temperature regulation response that makes machine oil is faster, the heat transfer more rapidly in time, prior art engine oil's the technical problem that heat dispersion is poor has been solved effectively. The utility model also discloses an engine of including this kind of lower crankcase.