Based on the effects of temperature and radiation on chrysanthemum growth, experiments with different cultivars, different stem number per plant, different planting density and different planting dates were carried out under greenhouse conditions in Shanghai from 2005 to 2006. A concept of physiological product of thermal effectiveness and photosynthetically active radiation (PTEP, MJ m-2) was proposed to develop a model with the PTEP as measurement scale for predicting the effect of stem number per area on dry matter production and partitioning of cut chrysanthemum. Independent experimental data were used to validate the model. The results showed that with increase of stem number per area, dry matter production increased but shoot fresh matter production per plant decreased. The model successfully predicted the dry matters of leaf, stem and flower as well as the fresh matter of shoot per plant in cut Chrysanthemum with different stem number and planting density. The coefficient of determination (R2) and root mean squared error (RMSE) based on the 1:1 line for the dry matters of leaf, stem and flower as well as the fresh matter of shoot per plant were 0.96, 0.95, 0.82 and 0.97, and 0863, 1.005, 0.201, 10.190 g·plant-1, respectively. The model can be used for optimizing light and temperature management for multi stem cut Chrysanthemum with different stem number and planting density under greenhouses conditions.