Abstract: The seedling of sweet potato is a segregated generation.The variation of its characters shows not only same tendency as that of its parents,but also significant positive correlation with the derived clones in many characters.This is the base of early selection and use of sweet potato seedling.The seedling can show three types on the tuber formation:tuber,inflated root and root.The percentage of tuber formation is various in accordance with its croosing parents and is less affected by the environment.Crossing breeding practice of sweet potato has shown that various types of clone differ greatly in the yield character.So we can get more high yield varieties from the tubers.Our investigation is more feasible and different from that of M.Granberry.We should regard the seedling stage as primary selectionstage for breeding.In this way the breeding period could be shortened and the breeding procedure could be speeded.

Key words: Sweet potato seedling, Characters variation, Early selection