In order to understand the photosynthetic characteristics of Chinese seabuckthorn , Russian seabuckthorn , and Russian seabuckthorn× Chinese seabuckthorn , research on the 3 species and their influence factors were conducted with Portable LI26400 Photosynthesis System in the loess hilly and gully region of Northern Shaanxi Province.Results showed that diurnal courses of photosynthetic rates , stomatal conductance , intercellular CO₂ concentration , and transpiration rate of the 3 species were the doublepeak type curves.Midday depression of Chinese seabuckthorn was light , and diurnal photosynthetic rates and afternoon photosynthetic rates were significantly higher than Russian seabuckthorn and Russian seabuckthorn× Chinese seabuckthorn ( p < 0.01) .Stomatal conductance , intercellular CO₂ concentration , and transpiration rate in afternoon for Chinese seabuckthorn were significantly higher than Russian seabuckthorn and Russian seabuckthorn×Chinese seabuckthorn ( p < 0.01) .Optimum stomatal conductance , air CO₂ concentration , and air relative humidity for photosynthesis of Chinese seabuckthorn were lower than Russian seabuckthorn , and optimum intercellular CO₂ concentration , transpiration rate , air temperature , and photosynthetic active radiation were higher than Russian seabuckthorn.Under the conditions of optimum stomatal conductance , intercellular CO₂ concentration , transpiration rate , and air CO₂ concentration , photosynthetic rates of Chinese seabuckthorn were higher than Russian seabuckthorn.Under the conditions of optimum air temperature , air relative humidity , and photosynthetic active radiation , photosynthetic rates of Chinese seabuckthorn were lower than Russian seabuckthorn.Midday depression of Russian seabuckthorn×Chinese seabuckthorn was lower than Chinese seabuckthorn and higher than Russian seabuckthorn , and photosynthetic rates were similar to Russian seabuckthorn in afternoon.Optimums stomatal conductance and air CO₂ concentration for photosynthesis of Russian seabuckthorn× Chinese seabuckthorn were higher than Chinese seabuckthorn and Russian seabuckthorn ; its optimum intercellular CO₂ concentration was lower than Chinese seabuckthorn and Russian seabuckthorn ; and its optimum transpiration rate , air temperature , air relative humidity , and photosynthetic active radiation were between Chinese seabuckthorn and Russian seabuckthorn.Under the condition of optimum stomatal conductance , photosynthetic rates of Russian seabuckthorn× Chinese seabuckthorn were higher than Chinese seabuckthorn and Russian seabuckthorn.Under the condition of optimum intercellular CO₂ concentration , transpiration rate , air temperature , air CO₂ concentration , air relative humidity , and photosynthetic active radiation , photosynthetic rates of Russian seabuckthorn×Chinese seabuckthorn were lower than Chinese seabuckthorn and Russian seabuckthorn.Photosynthetic rates of the 3 species had significantly correlations with stomatal conductance , intercellular CO₂ concentration , transpiration rate , air temperature , air CO₂ concentration , air relative humidity , and photosynthetic active radiation in forenoon , and their relationships might be described by a parabola.