Abstract: Taking the dry seeds of Poa pratensis Nassau carried by SZ-3 as the treatment and the seeds which on the earth as CK,three mutations were screened based on presentational characters from the plants treatment and asexual reproduction as PM1,PM2 and PM3.The effect of the space condition on the anatomical characters of the leaves and the ioszyme of peroxidase and esterase in leaves were observed and investigated.The results showed that compared to CK,the width of the leaves of the three mutations increased as the number of epidermis increased,the thickness of the leaves reduced as the average diameter of the mesophyllous cells decreased.The number of the bulliform cells in the leaves of PM2 and PM3 increased which changed the shape of the leaves.The results of the ioszyme of esterase showed that there were 11 bands in CK and the Rf value was 4.63%～47.22%;21 bands in PM1 and Rf value was 2.78%～68.52%;18 bands in PM2 and Rf value was 2.78%～67.59%;20 bands in PM3 and Rf value was 2.78%～63.89%.The results of the ioszyme of peroxidase showed that there were bands in CK and the Rf value was 59.74%～94.81%;8 bands in PM1 and the Rf value was 38.96%～94.81%;7 bands in PM2 and the Rf value was 48.05%～94.81%;8 bands in PM3 and the Rf value was 49.35%～94.81%.There were some same bands both in CK and the mutations,but there were also some other bands changed:some of them existed in the mutations but not in CK;some of them existed in CK but not in the mutations;and the activities of the ioszyme were changed greatly.All of these mutations were valuable to production application and genetic breeding.