The invention provides a quantitative fertilizer applying device for the planting industry and relates to the field of the planting industry. The quantitative fertilizer applying device comprises a cart plate, wherein a feeding hole communicated with the lower surface of the cart plate is arranged in the upper surface of the cart plate; supporting legs are fixedly connected on the lower surface ofthe cart plate; the ends, away from the the cart plate, of the supporting legs are fixedly connected with rotary shafts; rotary wheels are sheathed on the surfaces of the rotary shafts; a vertical column is fixedly connected on the upper surface of the cart plate; a fertilizer box is fixedly connected at the right side of the vertical column; a hole communicated with the inner part of the fertilizer box is opened in the top part of the fertilizer box. The quantitative fertilizer applying device provided by the invention has the beneficial effects that by a filtering layer arranged in a hopper, the filtration for fertilizer is achieved, and impurities can be prevented from entering the fertilizer box to cause blockage of a material guiding pipe; by arrangement of a pushing rod in a quantitative drum, the quantification for the fertilizer when in need of fertilizer application is achieved, so that waste is avoided; by arrangement of a reinforcing rod between the quantitative drum and afixed rod, the effect of fixing the quantitative drum is achieved.