The invention relates to the technical field of gravel removing machines and discloses a derrick type gravel removing machine for removing impurities. The gravel removing machine comprises a rack, wherein a motor is fixed at the bottom of one side of the inner surface of the rack through screws, the motor is electrically connected to an external power supply, and a first transmission wheel is fixed at the output end of the motor; and a main shaft is rotatably connected to an inner cross rod, above one side of the motor, of the rack, and a second transmission wheel is fixed at one end, in the front of the rack, of the main shaft. According to the derrick type gravel removing machine for removing the impurities, as for a structure, eccentric connecting rod transmission is adopted, the structure is simple and reasonable, the use of various parts is reduced, a fault point is reduced, and compared with existing gravel removing machines, the fault rate is lower; and because the structure issimple, in an application process, the energy consumption is lower, the noise is lower, and the overall efficiency of products is improved; and according to machining and operation modes, the energy consumption is not damaged, the operation is more stable, and the separation effect is better.