The effect of space environment on quality of japonica rice was identified based on the seeds flown on the 22nd satellite and the stable lines derived from three rice varieties flown on Shijian-8 satellite.The protein content,amylose content and taste value of the mutational lines and the control varieties were determined.The results indicated that mutational lines,compared with the control varieties,have obvious change in protein content and amylose content.Protein content in the offspring of induced varieties was higher than that in control.There were less low hardness lines in the offspring of low hardness varieties induced by space environment,compared with the control,while the offspring of poor taste or the high hardness varieties induced have more super-parents phenomena.Their taste and hardness reduced significantly.The taste value could be improved by space mutation and there were more chances to select good eating quality rice when poor taste value varieties were induced.