Abstract: Effects on M₁ generation of rice induced by space-flight was quite different from that induced by other commonly used physical and chemical mutagens, and even the effects of M₁ populations carried in different space-crafts were not exactly the same. To investigate the effects on M₁ generation of rice cultivar‘Hanghui 173’(Oryza sativa L. ssp. indica) whose seeds were carried in "ShenzhouⅧ" spacecraft (SP₁), seven characters including the germination rate, seedling height, plant height, length and width of flag-leaf, length and setting percentage of main-panicle were determined, and comparison of the SP₁ to 250 Gy ⁶⁰Co-γrays irradiated- M₁ generation (G1) and 1% EMS (Ethyl Methane Sulphonate) treatment - M₁ generation (E₁) was conducted. Further, to study the molecular mutagenic effect of "ShenzhouⅧ" carrying, 24 SSR markers were used to screening genetic variations within 100 mixed samples from 300 SP₁ individuals. The results showed that, contrast to the control, germination rate and main-panicle's setting percentage of the SP₁ decreased at significant and highly significant respectively, while remained five characters were found no significant difference. Comparative analysis showed that the "ShenzhouⅧ" carrying did not have effects on the late growth of SP₁ plants, whereas the late growth of G1 and E₁ plants were promoted leading to significant or highly significant differences on their plant height and length and width of flag-leaf. Amplification of 24 SSR markers showed that only one variation band was detected at locus RM267, and the corresponding variation rate was 0.014%.