Field experimental was carried out in winter season 2015-2016 in experimental field_coll. Of Agri. university of Al. Anbar (Alternative sit Abu_ Ghraib) in the clay silt to study the effect of four level of potassium fertilizer (potassium sulphate K2SO4) that is (0, 80, 120 and 240 Kg.ha-1) with three period of Irrigation (10, 20 and 30 days) in the growth and holds rapseed in the study used in a split -plots arrangement in randomized complete block design (R.C.B.D) with three replicates it fertilizer levels of potassium main plots and served as irrigation periods secondary plots. Adding of potassium fertilizer at level of 240 Kg.ha-1 leading. The highest average recipes plant hight (177.9 cm), leaf area (1912 cm2), number of siliqua (204.8 siliqua.plant-1), number of seeds in siliqua (26.53 seed.Siliqua-1), overall winning (1785 Kg.h-1), oil percent (42.778%), potassium percent (0.7078%). Irrigation period recorded (10 days) the highest value of recipes such as plant hight (168.6 cm), number of siliqua (194.9 siliqua.plant-1), number of seeds in siliqua (24.87 seed.Siliqua-1), overall winning (1674 Kg.h-1), oil percent (41.950%), potassium percent (0.6617%), . while the period of (20 days) leading highest average recipes such as leaf area (1472cm2).