Abstract: Plants of 4 wild Primula species were planted in the field in Kunming and the photosynthesis was tested with LI-6400 portable photosynthesis system.Species difference was found in light compensation point (LCP,μmol·m-2·s-1),light saturation point (LSP,μmol·m-2·s-1)and CO2 compensation point (CCP,μmol·mol-1) of photosynthesis. Primula pulverulenta Duthie had the highest LCP (28),the other 3 species had lower LCP(8-15).P.obconica Hance had both low LSP(80) and photosynthetic rate (Pn),and highest CCP(80).P.bulleyana Forr.and P.pulverulenta had both the highest LSP(500)and Pn,and intermediate CCP(64-69).P.forrestii Balf.f.had middle LSP and Pn,but the lowest CCP(54). The diurnal changes of Pn and transpiration rate (Tr) were one-peaked curves.Pn and Tr reached a maximum at about 10:00 and 13:00 respectively.Pn suppression at noon and in the afternoon was mainly caused by an increased stomata resistance,but this was the result of an increased carboxylation resistance at late afternoon. Pn was found closely correlated with leaf conductance to water,transpiration rate,photosynthetically active radiation, intercellular CO2 concentration and atmospheric pressure.