The root crown of forage legume is an important organ which connects underground root system and aboveground branches. And its morphological characteristic is closely related to yield of grass, overwintering ability, regeneration in spring and sustainable productivity of Medicago sativa L. Therefore, in order to understand the morphological mechanism on cold resistance of the root of Melilotoides ruthenica (L.) Sojak t㏊t is a relative species of M sativa, the root morphology of different growth years' M ruthenica had been observed and analyzed. It aims to provide theoretical basis to M. sativa genetic improvement.