0.804和0.759。By using self-developed portable instrument for crop nitrogen monitoring, the information of rice canopy reflectance spectra was obtained from the field experiments with two rice varieties and four nitrogen application rates, and the rice plant was sampled from each plot for measurement of leaf nitrogen concentration (LNC) simultaneously. The correlations and the quantitative relationships between LNC and rice canopy reflectance spectra were analyzed, and the performance of portable nitrogen monitoring instrument was evaluated. Results show that its ability in monitoring nitrogen is excellent, and its performance is steady in field condition. Testing the correlations between LNC and canopy reflectance spectrum of four characteristic bands included in the instrument, the correlations in the mono-band of 660nm, 710nm and 810nm are all more than 0.5 with a significance testing (p<0.01). During the all growth stages, the coefficients of determination R2between LNC and spectral vegetation index （VI）with double-bands are more than 0.7, especially in the flowering and mature stages (R2＞0.83). In the whole growth period, the VI are significantly correlated with LNC, such as NDVI（810,710）and NDVI(710,546), the determination of coefficients R2 are 0.804 and 0.759. 