The invention discloses a seed fertilizer dual-purpose type quantitative feeding device which comprises a detachable feeding device casing. The seed fertilizer dual-purpose type quantitative feeding device is characterized in that a feeding mechanism and a filling adjusting mechanism are arranged in the detachable feeding device casing, the feeding mechanism is composed of type hole wheels, an empty filling wheel, partition plates and a transmission shaft. The type hole wheels are separated through the partition plates, the type hole wheels and the empty filling wheel are separated through the partition plates, the filling adjusting mechanism comprises a filling adjusting plate, the filling adjusting plate is fixedly slantly installed above the feeding mechanism, a cover plate and a feeding box are installed at the upper end of the detachable feeding device casing, and an arch breaking mechanism is installed at the bottom of the feeding box. The seed fertilizer dual-purpose type quantitative feeding device is reasonable in design, the oblique sawtooth-shaped type hole wheels in the feeding mechanism are adopted to be combined with Z-shaped arch breaking structure of the arch breaking mechanism, dual-purpose feeding of wheat and rape seeds and the like and the particle fertilizer can be achieved well, and the overall structure and manufacturing cost of a seeder are simplified.