Abstract: 【Objective】Maize genotypes have been shown to differ in photosynthetic characters. Grain yield in maize was mainly attributable to photosynthetic efficiency during grain-filling period. So it was important for improving photosynthetic efficiency to pick out the hereditary regularity and combing ability in the main photosynthetic characters of maize during the late stage. 【Method】8 inbred lines with different photosynthetic rate were used as parents to make 36 combinations by (1/2)n(n+1) diallel crossing model. By using Griffing Ⅱ and Hayman methods, combing ability and genetic parameters were analyzed in 4 photosynthetic characters. 【Result】It was indicated that the inheritance of chlorophyll content fit to “additive-dominant” model, both additive and dormant effect were important and it was determined by one complete dominant gene. The inheritance of Pn also fit to “additive-dominant” model, it was controlled by 1 major gene; but SW was not conformed to “additive-dominant” model, it was controlled by many minor genes and few major genes. Both Pn and SW depended on the non-additive genetic effect and there were predominant effects. The h2N% was ordered from high to low as Chl, SW, Pn. The analysis of combining ability showed highly significant GCA and significant SCA effects indicating the importance of additive and dominant genetic components in controlling photosynthetic characters. There were 5 inbred lines with high GCA and high average value, such as B114, Chang7-2, Luyuan92, Huangzao4 and A150. The comparison of the combinations with high photosynthetic efficient showed that such combinations involved at least one parent with high positive GCA effect. 【Conclusion】The results revealed that it was feasible to use highly photosynthetic efficient inbred lines to achieve combination with high photosynthetic efficiency. It was necessary to make as many crosses as possible.