Abstract: Abstract: In order to seek the effects of CO2 capture agent on photosynthesis, water use efficiency and mineral nutrition of cowpea in greenhouse, analyzed the response of every growth index of cowpea on different treatments based on ‘cowpea 28-2’. There were four treatments, CK no fertilizer, T1 applied organic fertilizer, T2 organic inorganic fertilizer (N 176.3 kg/hm2 P2O5 68.1 kg/hm2 K2O 144 kg/hm2), T3 applied organic fertilizer before planting and “Photo-carbon Fertilizer” during the growth period of cowpea. The result indicated that “Photo-carbon Fertilizer” could capture free CO2 in the atmosphere around the stem, the growth of cowpea better, photosynthesis increased significantly and photosynthetic noon break disappeared, Cond dropped and leaf boundary resistance increased while transpiration rate decreased, at the same time, leaf water use efficiency was increased by 20% than CK, significantly (P<0.05). Leaf temperature rose and activated blade internal enzyme systems activity, through measuring, the enzyme activity of POD and SOD increased by 11.6%-34.5%, 11.6%-19.3% while chlorophyll a, chlorophyll b, chlorophyll (a b) and chlorophyll (a/b) decreased by 4.3%, 2.76%, 4.3% and 0.6% than CK respectively, but the difference was not significant. The content of N, P, K, Ca and Mg decreased by 27.6%, 35.7%, 54%, 1.9%, 6.18% than CK. The comprehensive analysis of every index indicate it is significant for “Photo-carbon Fertilizer” to promote the facilities of cowpea growth, improve water use efficiency and quality improvement.