To quantify dry matter partitioning among different fruit trusses and to improve production efficiency of greenhouse tomato, three experiments were carried out for over-winter, early-spring and spring-summer crops, respectively. Total dry weights of stem, leaves, fruits within a source-sink growth unit (one fruit truss and three leaves just below the truss) were measured during growing periods. A simulation model of total biomass and the partitioning among stems, leaves and fruits within a growth unit was constructed by combining a classical model of dry matter production in a leaf with the GreenLab model of dry matter partitioning. Our combined model was tested against measured data. The slope and coefficient of determination (R2 ) between simulated and measured biomass of the whole plant for three experiments were 0.93 and 092, respectively. The slopes between simulated and measured dry weight of stems, leaves and fruits within source-sink growth units and dry weight of root of the plant were 0.85-0.89, and the relative error between them was 5.3%, 5.6%, 8.1% and 3.6%, respectively. These results suggested that our model could be used for optimizing fruit yield of greenhouse tomato production.