The utility model relates to the technical field of mechanical equipment. The foundation drilling guide drill bit comprises a drill bit body, in the prior art, a rotating shaft is easy to incline; further, the drilling perpendicularity deviation of the drill bit is more. Wherein openings are formed in the top and the bottom of the guide pile casing, a cavity is formed in the guide pile casing, a rotating shaft is fixedly installed in the cavity, a first transverse plate and a second transverse plate are fixedly installed on the two sides of the rotating shaft respectively, and a plurality of drill bits are fixedly installed at the top of the first transverse plate and the top of the second transverse plate respectively. The utility model has a simple structure, convenient operation, the guide protective cylinder is fixedly connected with the rotating shaft; in the downward rotating process of the guide pile casing, the position of the guide pile casing cannot deviate, then the positionof the rotating shaft cannot deviate when the rotating shaft drills a well downwards, the drilling perpendicularity of the rotating shaft can be guaranteed through the guide pile casing, the situation of serious perpendicularity deviation cannot happen, drilling work does not need to be conducted again, and in other words, the input cost can be saved.