Abstract: The effect of two pear rotstocks ‘Calleryana’ and ‘Betulaefolia’ on photosynthetic properties of young ‘Hosui’ under salinity was measured by portable photosynthesis systems CIRAS-1．The results showed that：(1)There are obvious discrepancy between Pyrus betulaefolia and P.calleryana efect on the photosynthetic properties of Hosui blade; (2)Pn，Gs，Tr，and CE were higher in Hosui combined with P.betulaefolia (H-B)than in Hosui comb ined with P.calleryana (H-C)under the same conditions，H-C with higher Ci than H-B under high salinity．(3)Photosynthesis of pear blade was inhibited by salinity most cause for stomatal limitation under low salinity at early time，and most cause for nonstomatal limitation under high salinity and low salinity at anaphase；(4)In anaphase oftreatment，the discrepancy between P．betulaefolia and P.calleryana efect on photosynthetic properties was dimi nished under severe salinity．

Key words: Pear, Rootstock, Photosynthetic properties, Salinity, Stomatal limitation, Nonstomatal limi tation