[en] 5000 dry seeds of Leymus chinensis were carried by No. 21 recoverable research satellite (Express by SP) and the same number on the earth as control (Express by CK). Investigation of cytogenetic characteristics showed that space mutation could increase the number of micronucleus and micronucleus rate,germination rate of Leymus chinensis which had been treated by space mutation was 13.33%,higher than that of control (Germination rate of CK was only 3.33%). Biological characteristics such as plant height, leaf length,leaf breadth,spike length, above ground biomass, number of tillers and growth velocity were also investigated,the results showed that all of those indexes except number of tillers increased due to space mutation.Germination rate,number of cell micronucleus and chromosome variation rate of Leymus chinensis increased after space mutation which were beneficial to variation of Leymus chinensis. Also space mutation redounded to increase productivity and seed yield of Leymus chinensis in a way. (author)