Abstract. Net Photosynthetic rate(Pn), relative electrical conductivity and MDA content of 11 fennel varieties were tested using LI-6400 portable photosynthesis system. The results showed that Pn of XJ0710 has distinct difference with other varieties in which there is no obvious difference. But the relative electrical conductivity and MDA of the varieties have obvious difference. Under environmental stress, all of the varieties had different stress resistance. This study provides reference for selecting good fennel varieties