Cadmium’s (Cd) impact on the photosynthetic activities of energy plant maize was investigated in pot experiments containing different Cd contaminated levels during the whole growth period. The results showed that the ability of photosynthesis was not obviously inhibited by elevated Cd stress. Net photosynthetic rate (NPR) was decreased with the growth of maize, while transpiration rate (TR), stomatal conductance (gs>) and intercellular CO2 concentration (Ci) were enhanced in heading period, then decreased in maturity period. The change of fluorescence quenching and photosystem II (PSII) efficiency was consistent with NPR. Thus, the influence of photosynthesis under Cd stress mainly depended on the response of PSII reaction centre.