The utility model discloses a disc cutter formula composite drill bit suitable for bad ground, including the drill bit body, extend to a plurality of wing of drill bit body, relative drill bit body rotates the disc cutter who connects, and arrange hydrophthalmia or the nozzle on the drill bit body, be provided with the first group's cutting teeth of a plurality of on the wing, the wing cloth flank of tooth sets up the slot and is used for fixing first group cutting teeth, disc cutter comprises the disc cutter body and the disc cutter tooth that sets up above that, have at least the body wheel profile of a wing and the body wheel profile of at least another one wing to have at least one coincidence region in common coverage, and at least one coincidence dot OR coincidence is regional. This kind of constitutional features can make the drill bit with the work of asynchronous cutting mode, can not only increase vertical wearing and tearing length of drill bit, and extension bit life enables the drill bit in addition and is in the high specific pressure state of creeping into at whole tool joint, strengthens the ability that rock -entering stone was invaded to the drill bit to make the drill bit all obtain improving in the drilling speed and the life -span of bad ground.