The experiment was conducted to investigate the proximate composition of oil cake of Brassica cultivars Tori-7, SAU Sharisha-1 and Sampad. Data on different characteristics were recorded to find out the differences for different cultivars of Brassica campestris. The highest (8.6%) free sugar was recorded in the cultivar Sampad, while the lowest (7.0%) was recorded in SAU Sharisha-1. The lowest (11.35%) crude fibre of seed was recorded in SAU Sharisha-1. On the other hand, the highest (13.20%) crude fibre was recorded in the cultivar Sampad. The maximum (34.15%) polysaccharide of seeds was recorded in Tori-7 while the minimum (31.00%) was recorded in the cultivar Sampad. The β-carotene content of the released cultivars and lines varied from 174.00 µg to 261.00 µg. The highest (261.00 µg) β-carotene of seed was recorded in SAU Sharisha-1 which was statistically identical (253 µg) with Tori-7, while the lowest (174.00 µg) was recorded in the cultivar Sampad. Total amount of vitamin C concentration in different cultivars of Brassica varied from 0.50% to 1.00%. The highest (1.00%) vitamin C of seed was recorded in SAU Sharisha-1. On the other hand, the lowest (0.50%) was recorded in the cultivar Sampad which was closely followed (0.80%) by Tori-7. The highest (43.13%) protein content was recorded in SAU Sharisha-1, while the lowest (34.00%) was recorded in the cultivar Sampad. The highest (6.90%) total nitrogen of seed was recorded in SAU Sharisha-1 and the lowest (5.44%) was recorded in the cultivar Sampad. In respect of ash minerals the highest (0.512%) calcium of Brassica seed was recorded in Sampad, while the lowest (0.377%) was recorded in the cultivar SAU Sharisha-1. The highest (0.408%) magnesium of seed was recorded in Sampad and the lowest (0.321%) was recorded in the cultivar Tori-7. The highest (1.65%) potassium of seed was recorded in Sampad, while the lowest (1.50%) was recorded in the cultivar Tori-7 and SAU Sharisha-1. The highest (1.62%) phosphorus of Brassica seeds was recorded in Sampad, while the lowest (0.83%) was recorded in the cultivar Tori-7. The highest (0.036%) zinc was recorded in Sampad and the lowest (0.012%) was recorded in the Tori-7. The highest (0.009%) copper was recorded in Sampad, while the lowest (0.001%) was recorded in the cultivar SAU Sharisha-1. The highest (0.210%) manganese was recorded for Sampad, while the lowest (0.016%) was recorded in the cultivar Tori-7. Variety Sampad contain 0.141% iron among the variety that were used in this experiment and the other variety did not contain any amount of iron. Considering all parameters under study, SAU Sharisha-1 performed better than all other cultivars.