The experiment was sown in 2018 and 2019 summer seasons at Agric. Exp. and Res. St., at Giza, Egypt to study the effect of field weathering on seed quality of soybean. Soybean Giza 111 cv. was harvested in physiological maturity (PM), 7, 14 and 21 days after PM. Harvesting at 7 days after PM produced greatest normal and green seed % but delaying harvesting after that increased defective seed%, EC value and decreased seed weight. Highest seed germination % and normal seedling%, longest and heaviest seedling were recorded from the seed harvested at PM which showed highest oil and protein content and highest values of seedling vigor index. The variation in the period from flowering to threshing and the day temperature during the period were participated with a great percentage of variation in the most of these traits.