Abstract: The genetic diversity of Qiancao No.1 Festuca arundinacea after spaceflight was analyzed by RAPD molecular marker technique, and the influence of space environment on genetic diversity was discussed. The results showed that polymorphic bands accounted for 83.85% of the amplified bands using RAPD primers. The similarity coefficient of 34 samples ranged from 0.536 4 to 0.741 1, indicating that the space flight of Qiancao No.1 Festuca arundinacea could cause changes in its genetic material, and different degrees of genetic variation occurred in each line after mutation, and materials suitable for breeding targets could be selected from the lines after space flight mutation. RAPD cluster analysis divided the tested materials into seven categories. On the whole, the lines with similar characters could basically cluster in one class, showing certain character differences.