The present study was carried out at the experimental Farm of Agriculture Research Station, Itay El-Baroud, EL-Behiera Governorate, Egypt, during the two summer seasons of 2017 and 2018 to study the effect of the three planting dates 1^st , 20^th May and 10^th June and foilar application of silicon at the rate of  (100, 200, 300 mg/L and water spray = control) on yield and quality of soybean cv. Giza 111. This experiment was laid out in split plot design with three replications.The three planting dates were distributed in main plots, while the four silicon concentration were allocated in the sub plots. The obtained results showed that planting soybean during May 1^st and 20^th exceeded the late planting date (10^th June) for all yield and yield components traits in both seasons. While, the late planting date in 10^th June exceeded the early planting dates in May for Si contents and oil percentage in both seasons. Spraying high level of silicon on soybean plants led to a significant increase in 100-seed weight and seed yield/fed, while spraying 100 mg/L of silicon gave the highest percentage of oil in seeds in both seasons. The increase in the level of silicon from 100 to 200 and 300 mg/L resulted in a significant increase in the number of pods / plant in both planting dates (1^st and 20^th May), while the highest level of silicon 300 mg/L led to a significant increase in the 100-seed weight in the 1^st and 2^nd planting dates (1^st May and 20^th May) in both seasons. The results showed that the highest seed yield/fed was obtained by spraying 300 mg/L of silicon at the 1^st planting date (1^st May). Finally, the highest oil percentage was presented in the 3rd planting date was shown on 10^th June by spraying 200 mg/L of silicon followed by spraying 200 mg/L at the first planting date in both seasons.