Abstract: For the stems upright sexual performance of different varieties of Paeonia lactiflora under facility cultivation， Dafugui and Taohuafeixue were used to study the differences in morphological characters， anatomical structure， mechanical properties and composition. The results showed that the two varieties were obviously different in stem morphological characters. The better orthostatic performance variety Dafugui was shorter， its stem was thicker and basal internode of total internode length ratio was lower; anatomical analysis showed that its number of vascular bundle， thickness of epidermis cells and cortex cells were higher than Taohuafeixue; stem mechanics analysis showed that two varieties also had obvious difference， the compressive strength，bending strength and puncture strength of Dafugui was better than that of Taohuafeixue; stem composition determination showed that the lignin and cellulose content of Dafugui were higher than that of Taohuafeixue. Correlation analysis revealed that stem lignin and cellulose content， bending strength on upper stem section 5 cm， pith of stem area ratio， basal internode of total internode length ratio were highly correlated with stem orthostatic performance. Therefore， in the screening and breeding of Paeonia lactiflora cut flower varieties under facility cultivation， we should pay more attention to these characteristics.

Key words: Paeonia lactiflora, stem, orthostatic performance, facility cultivation