The invention relates to a direct injection engine cam shaft bearing cap which comprises a bearing cap body. An upper arc sealing face, a lower sealing face and a rear sealing face are arranged on the bearing cap body, wherein the upper arc sealing face can be attached to an air cylinder head cover above the bearing cap body, the lower sealing face can be attached to an air cylinder head below the bearing cap body, the rear sealing face can be attached to a high-pressure oil pump base behind the bearing cap body, and an arc concave face matched with a cam shaft neck is arranged on the lower sealing face. First installing holes in the vertical direction and second installing holes in the front-back direction are formed in the left side and the right side of the bearing cap body respectively, and ventilation holes are formed in the rear sealing face of the bearing cap body. When a high-pressure oil pump is arranged at the rear end of the cylinder head, the cam shaft bearing cap ensures that the seal between the high-pressure oil pump base and the air cylinder head, the cam shaft and the air cylinder head cover is reliable, and the pressure between an inner cavity of the high-pressure oil pump base and the interior of an air cylinder head system is balanced.