The seeds of maize single hybrid Chuandan No. 9 were carried into space in 1996 by satellite. After the seeds were planted in field in comparison with travel in space seeds which was not carried into space. Fortunately, male sterile plants were discovered in one of the ear rows. The stability of male sterile expression was observed in different years, different locations and different generations. In order to analysis the genetic characteristic of male sterility, test cross, sister cross, back cross, reciprocal cross and self-pollination were conducted with these male sterile plants. The results showed that the male sterility was stable in different years and different locations, it is inheritable from generation to generation. The sterility is controlled by a single nuclear recessive gene. The appearance of male sterile mutant is the conclusion of gene mutation which happened in nuclear by space flight. This mutant material always accompanies with lower plant height.