One of the methods of producing edible onions is using seeds. From the point of view of crop production, flower and seed formation has a high value. In order to investigate the effect of initial weight of edible onion bulbs (White Spanish cultivar) on yield components and seed quality, a study in two cropping years 1392-1391 and 1393-1392 in the research farm of Gorgan University of Agricultural Sciences and Natural Resources in a randomized complete block design with three Repeat was examined. The results of the present study showed that the highest plant diameter, plant height at 18 and 50 days after planting, flowering stem height, flowering stem diameter, diameter of flower and seed flowering, number of seed flowers, multiplication in 50 and 70 days after Planting and germination rate coefficient was related to onions with high bulb initial weight (175-150 g). Smaller bulbs had the highest 1000-seed weight, seedling dry weight and number of natural seedlings. Small bulbs, despite producing fewer seeds, produce larger, higher quality seeds. Therefore, it is suggested to use small onions to produce high quality seeds. Also, according to the obtained models for 1000-seed weight and number of natural seedlings and proper adaptation of these models to the measured values ​​(0.80 and 0.94, respectively), the values ​​of these indicators can be predicted based on the presented models.