Leaf is one of the most important photosynthetic organs of rapeseed(Brassica napus L.).In order to quantify the relationships between the leaf morphological parameters on main stem for rapeseed and the corresponding leaf biomass, the field experiments on varieties, transplanting densities, and fertilizer were conducted in 2011 to 2012, and 2012 to 2013 seasons.The biomass-based leafmorphological parameter models for rapeseed on main stem were constructed through observing leaf length, maximum leaf width, and leaf petiole length under various treatments, and analyzing the relationships between leaf morphological parameters and the corresponding leaf biomass.Due to both of the leaf length and leaf width were positive proportional to the square root of the corresponding leaf biomass, meanwhile the leaf petiole length was positive proportional to the corresponding leaf length, thus, the changes in the leaf length, the maximum leaf width, and the leaf petiole length with the square root of the corresponding leaf biomass for different treatmentscan be described with linearfunction.The biomass-based leaf morphological parameter models were validated using independent experiment data.The mean absolute difference (da) between the estimated and observed values were-0.87 cm forleaf length, -0.33 cm for maximum leaf width, and 0.03 cm for leaf petiole length, and the ratio of da to the mean observation (dap)between the estimated and observed values were 7.76%, 6.54%, and 0.46% for the above parameters, respectively, which indicated that the model developed in this paperrevealed satisfactory predictions ofleaf length, leaf width, and leaf petiole length.The research can provide a mechanistic method for linking the rapeseed growth model with the morphological model using organ biomass, and lay a foundation for the establishment of functional-structural plant models of rapeseed.