Abstract: The aim is to analyze the light distribution and photosynthesis characters of cucumber canopies by using functional-structural plant models and to provide a theoretical basis for optimizing the planting density of cucumber in winter. Virtual cucumber canopies structure model under the treatment with different plant spacing and row spacing in autumn and winter was constructed by using parametrization method. Combining with light distribution model and photosynthesis model, the influence of plant and row spacing change on leaves distribution of canopy, light interception and photosynthetic rate was simulated and analyzed. The results showed that as plant and row spacing increased, light condition in the canopy was improved, meanwhile, light interception of leaves of azimuths towards north direction and inside of rows was promoted. The distribution frequency of leaves in the north and inside the row increased obviously. From the light interception per plant, the change of plant and row spacing increased the light interception by 34.78% and 23.18% , respectively. The simulation result of light interception was combined with photosynthesis model, and then the optimal plant and row spacing was obtained, which was 45.70 cm (plant spacing) and 43.22 cm (row spacing), respectively.