The utility model discloses a novel connecting structure for petroleum drilling machine substructure foundation beams, which consists of a front connecting beam, a rear connecting beam, a pin, a lug plate, bolts, a connecting plate and the like, wherein the front beam and the rear beam are mixed and connected via a combination of the pin and the plug plate, and a combination of the connecting plate, the bolt and nut. A novel connection mode is formed by aid of a mixed connection structure of the combination of the pin and the lug plate and the combination of the bolt and the connecting plate, bending stress characteristics of the drilling machine substructure foundation beams are utilized sufficiently, the connecting structure for the beams is optimized, stress thereof is more reasonable, load bearing capacity of the connecting structure for the beams is enlarged within a limit height space of the beams, and length of one side of each beam can be reduced properly when in length limitation during transport. The novel connecting structure is applicable to the field of large-sized mechanical engineering technology, petroleum drilling machines and coal source exploration and the like.