The invention discloses an online detection device for soil elements, which comprises a limit plate, a control detection room, a pulley, a laser collection box, a laser emitter, a pulley, a fixing bolt, a dust cover, a rotating shaft, a soil-breaking blade, a belt, and a punching knife , the support rod vertically passes through the limiting plate and is fixedly connected to the top of the dust cover at the bottom of the limiting plate, and a laser emitter is fixedly connected to the bottom of one side of the limiting plate, and the same A laser collection box is placed on the top of the side, a motor is fixedly connected to the center of the top of the limiting plate, a pulley is fixedly connected to the output shaft of the motor, the pulley is connected to the rotating shaft through a belt, and the rotating shaft is flexibly connected On the support rod, the support rod is fixedly connected to the bottom of the dust cover, the surface of the rotating shaft is fixedly connected with a soil-breaking blade, the control detection chamber is welded and bonded to the right side of the limit plate, and the A punching knife is fixedly connected to the center of the bottom of the control detection chamber.