Abstract: The effects of space electro static field and CO₂ on cucumber（Cucumis sativus L.）seeding's photosynthesis were studied in plastic chambers. The results showed space electro static field can significantly promoted cucumber，s net photosynthetic rate（Pn），strengthened the plant's photosynthesis，and each treatment's diversity elevated too.With the increasing of photosynthetically active radiation（PAR），the diversity of photosynthesis was mainly caused by non-stoma restriction in each treatment。There were no significant differences on cucumber's apparent quantum efficiency（AQY）which treated by electro static field and CO₂。Electro static field decreased obviously largely CO₂ saturation point（CSP）and CO₂ compensation point（CCP）in cucumber，also increased obviously plant's carboxylation efficiency（CE） and Max regeneration velocity of RuBP，plant's photorespiration rate（R_P）has a marked rise. CO₂ can decreased significantly cucumber's light compensation point（LCP）。

Key words: cucumber, electro static field, CO₂, photosynthetic characteristics