Abstract: Castor (Ricinus communis) is monoecism crop with few pistillate plants without male flowers and propagation, which can not be produced hybrid seed.The suitable marcottage time in open field in Kunming was found in this paper by the study of different time of marcottage of pistillate plants of castor. By asexual propagation of pistillate plants, the pistillate plants are propagated without maintainer lines, and is maintained male sterile, which can be used in hybrid seed production.