Nitrogen was an essential element for the growth and development of miniature potted roses. It was very important to monitor the changes of plant nitrogen nutrition in real time and accurately estimate the nitrogen nutrition content in the cultivation and production. Four nitrogen application treatments were set up to analyze the impact of nitrogen application amount on the growth and development of miniature potted roses. The leaf SPAD values at different growth stages and different leaf layers of four different miniature potted roses were measured. Linear and nonlinear regression analysis methods were used to structure leaf nitrogen content estimation models for single and mixed cultivars based on leaf SPAD values. The critical nitrogen content was evaluated by the nitrogen saturation index. The results showed that the vegetative growth tendency of four different miniature potted roses cultivars during the whole growth period wassimilar，and the character indexes were different under different nitrogen application levels. With the increase ofnitrogenapplication，both the nitrogen content in leaves and the SPAD value in leaves increased first and then stabilized. There was a significant correlation between the leaf SPADvalue and the leaf nitrogencontent，and it was different in different layers. The comprehensive model constructed by using four varieties was better than the single model in generality. The lower leavesat S1 and S2stages，and the upper leaves at S3 and S4 stages had higher regression coefficient between SPAD values and leaf nitrogen content. The constructed models were y=0.0009x2+0.6115x+0.8047，y=0.002x2+0.7118x+2.3382，y=0.1279x1.4938，y=-0.0015x2+0.5204x+3.7738，respectively. It was reliable to estimate the nitrogensaturation index by the polynomial model. Inconclusion，nitrogen applicationlevels， growth period and leaf position all affect the correlation between SPAD value and leaf nitrogen content. The comprehensive model of leaf nitrogen content estimation established by using four varieties could be used as a universal model. The polynomial equation of the nitrogen saturation index was more accuratein nitrogendiagnosis，and provides theoretical data for real -time diagnosis of nitrogen nutrition in miniature potted rose.