Abstract: In order to explore the difference in roots of different varieties of oilseed rape in response to nitrogen and its contribution to the yield, sand cultural experiment was conducted to study the morphological and physiological characteristics of roots of 3 oilseed rape varieties under five levels of nitrogen supply. The results showed that the root weight, root volume, total absorbing surface area of roots and active absorption area increased with increasing nitrogen level. With the increasing of nitrogen level, the root vitality of varieties H29 and 231 at seedling stage increased first and then decreased, but that of variety bin270 decreased first and increased afterwards, the root vitality of varieties H29 and bin270 at full flowering stage decreased first and increased afterwards, but that of variety 231 increased first and decreased afterwards. Under the same nitrogen level, the root weight, root volume, total absorbing surface area of roots and active absorption area of variety bin270 were the largest; variety 231 showed the smallest total absorbing surface area of roots and active absorption area, but the highest kernel yield. Kernel yield had positive correlations with the root indexes at seedling and full flowering stages, and the contribution of the root weight, root volume, total absorbing surface area of roots and active absorption area to kernel yield were larger than that of the root length and primary lateral root number.