13 species of urban greening plants in Hohhot were selected for study. The photosynthetic physiology and ecology indexes of plants were measured by using LI6400 portable photosynthesis system and the carbon fixation capacity of the plants were quantitatively studied. The effects of plant photosynthesis on the carbon fixation were studied. The factors affecting the efficiency of carbon sequestration were analyzed. The order of carbon sequestration efficiency was determined. The result indicated that: (1) different plants had different trends in daily carbon fixation, Poa pratensis, Hemerocallis fulva, Paeonia lactiflora an single peak curve， and Platycladus orientalis, Picea asperata, Sabina chinensis, Pinus tabuliformis, Sabina vulgaris, Forsythia suspensa, Syringa oblata, Sophora japonica, Salix babylonica, Populus alba var. pyramidalis had doublepeak curve. From June to November, the trend of carbon sequestration of each plant was basically the same that the high value of carbon sequestration appeared around June, and before or after September. (2) Carbon sequestration of plants: Forsythia suspensa> Sophora japonica> Populus alba var. pyramidalis> Syringa oblata> Pinus tabuliformis> Sabina vulgaris> Sabina chinensis> Paeonia lactiflora> Hemerocallis fulva> Salix babylonica> Platycladus orientalis> Picea asperata> Poa pratensis； (3) there was a significant correlation between carbon sequestration and photosynthetic rate, transpiration rate and air temperature. According to the main species of carbon dioxide fixation and oxygen release analysis showed that the plant configuration, carbon fixation and oxygen release of relatively strong plants as the preferred plant (the arbors optimum with Sophora japonica, evergreen arbors with Pinus tabuliformis, the shrubs optimum with Forsythia suspensa, the herbaceous plants optimum with Paeonia lactiflora), while carbon fixation ability could be used as a longlived species and ornamental species, which were suitable for selection for a large area of green．The purpose of this study was to provide reference for the selection of urban greening plants, to provide theoretical support for the construction of urban greening plant communities, and to provide scientific basis for the construction of urban ecological gardens．