The photosynthetic parameters of 'Flame Seedless' and 'Red Globe' grape leaves in oblique single cordon (OSC) vine along the ditch and traditional single cordon (TSC) vine were determined using the CIRAS-2 photosynthetic system. The photosynthesis of leaves was studied using the Gaussian multi-peak model, Yezipiao's model, and the extended Freundlich's model fitting methods. The results showed that the correlation coefficients of the three data models fitting the field data were between 0.89 and 0.97. The three models can be used to analyze photosynthesis of grape leaves. In this paper, the physical significance of indicators obtained by extended Freundlich's model fitting was verified. The grape leaves of OSC showed higher daily accumulation of photosynthesis, maximum photosynthetic rate, saturated light intensity, light adaptation range, and light-use efficiency than that of TSC. Grape leaves under OSC can better adapt to the environment.