Abstract: Through different pairing groups of short castor gene and high castor,planting and researching plant height seperation test of their offspring,study the master gene heredity rule of castor high and short character.As a result,in F1 population,plant height doesn＇t separate,they are all of high character;in F2 populution shows two character separating,and character separation tally with 3：1,in BCF1 population high and short piant separation also happen,and tally with 1：1.Thus we infer that castor high and short character is controlled by one pair of allele gene,high plant is controlled by dominant gene T,and short plant is controlled by recessive genet.