Abstarct: Drought stress is one of the most important environmental factors restricting crop growth and development. The use of nutrients such as potassium silicate to produce grain yield and to reduce the side effects of drought stress on canola can play a role in increasing production and quality. In order to study the effects of terminal drought stress and foliar application of potassium silicate on yield and canola spring genotypes components, a factorial split-plot test was conducted in Karaj-Iran in a randomized complete block configuration with three replications for two years of cultivation (2016-2018).The irrigation was performed at two levels in this study, including routine irrigation (control) and interruption of irrigation from the pod formation stage. Potassium silicate foliar application at two levels comprised of 0 and 4 g liter-1 in factorial status in main plots and five Brassica napus L. genotypes including OG×AL, RGS×SLM, DALGAN, RGS003 and RGS×Okapi in subplots. The results of this study showed that the studied traits were affected by applied treatments, so that the highest grain yield (5620 kg/ha), oil yield (2601 kg/ha), oleic acid (68.16%), linoleic acid (18.68%) was obtained in full irrigation conditions with foliar application in OG×AL genotype. RGS×SLM genotype was also the best genotype under stress conditions with foliar application of potassium silicate. End-of-season drought stress increased stomatal resistance, leaf proline, leaf soluble carbohydrate, canopy temperature, grain glucosinolate and decreased total chlorophyll content, relative leaf water content, catalase enzymes, superoxide dismutase and peroxidase. Finally, our study showed the beneficial effects of Potassium Silicate in improving the drought tolerance of canola plants, especially at the end of the season. This can provide a basis for attempting new strategies to reduce the damage from drought and create a functional lixnk between the role of silicon, physiological response and tolerance to drought stress in canola plants. OG×AL genotype is recommended under normal irrigation conditions and Potassium silicate foliar application. RGS×SLM and DALGAN genotypes are recommended under late-season drought stress conditions (With holding irrigation from silique formation) and potassium silicate foliar application.