By studying the effects of different cultivation substrates, sowing densities and drought stress on the output of onion bulblets, we screened the optimal seedling density, cultivation substrate and drought stress level, so as to realize the intensive and efficient production of small bulbs, and to provide sufficient small bulbs for the development of high-density mechanization of transplanting, with a view to laying the foundation for the realization of the mechanization of planting of onion bulblets. The study was carried out in the greenhouse with different cultivation substrates, different sowing densities and drought stresses. After preparing sufficient bulblets, the bulblets were categorized and field experiments were carried out to study the effects of different bulblet sizes and different sowing directions of the bulblet root system on onion yield, photosynthetic characteristics and quality.