Abstract: Grafted cucumber in greenhouse was used as the test materials, and there were four treatments were set, including high temperature, high temperature+CO₂ enrichment, normal temperature+CO₂ enrichment and normal cultivation as the control.The diurnal variation of photosynthesis and stomatal movement of cucumber leaves under different treatments in greenhouse were studied, in order to provide reference for the subsequent study of stomatal movement regulation mechanism.The results showed that from 10:00 to 16:00,the net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration and stomatal aperture of cucumber leaves under high temperature+CO₂ enrichment were significantly higher than those of the control.The net photosynthetic rate under high temperature was significantly lower than that under control,while the net photosynthetic rate under normal temperature+CO₂ enrichment increased but the difference was not significant.The combination of high temperature and CO₂ enrichment could promote stomatal opening and significantly improve photosynthesis of cucumber leaves,but the effect of simple high temperature or CO₂ enrichment was not obvious.