The utility model discloses a coulter limiting device of a peanut combined harvester, which comprises a peanut vine conveying shute, a lift cylinder, a limiting assembly, a base plate and a coulter. The coulter limiting device is characterized in that the coulter is mounted at the front end of the peanut vine conveying shute; one end of the lift cylinder and one end of the limiting assembly are mounted on the base plate, and the other ends thereof are mounted on the peanut vine conveying shute; and the limiting assembly comprises a screw rod, a guide sleeve and a limit nut. In the limiting process, when the lift cylinder is lifted, the peanut vine conveying shute and the coulter are lifted correspondingly; and when the lift cylinder falls, the peanut vine conveying shute and the coulter fall correspondingly. In the lifting and falling processes, the screw rod is rotated, the limit nut moves up and down correspondingly, and the guide sleeve is pressed on the limit nut, so as to complete limiting movement. The utility model has the beneficial effects that the earthed depth of the coulter can be adjusted according to ground condition and peanut growing condition, so as to ensure that the earthed depth of the coulter is in favorable digging state all the time, thereby not only fully digging the peanut without damaging the peanuts, but also guaranteeing the normal work of the power matched with the peanut combined harvester so as to improve harvest effect.