Abstract  [Aim]  Models for monitoring the population size of the white-backed planthopper (WBPH), Sogatella furcifera, were established using the spectral reflectance of rice leaves to provide methodological support for the spectral monitoring of rice planthoppers. [Methods]  The degree of WBPH damage to rice plants was manually controlled by transplanting different numbers of third instar nymphs onto the tillering and booting stages of rice plants. Reflectance measurements were taken from the fourth leaf from top (4LFT) and all leaves of the rice plant 1-4 weeks following WBPH infestation using an ASD FieldSpec handheld spectroradiometer in a dark room. Correlation analysis was used to determine the relationships between leaf spectral reflectance, spectral vegetation index, and the number of WBPHs on the rice plant. Regression models for monitoring the WBPH population size were established using the stepwise regression modeling method based on the spectral vegetation index. [Results]  Spectral reflectance from the 4LFT and all leaves of a rice plant was unable to characterize a population size of up to 20 WBPHs per plant after 1-2 weeks of damage during the tillering stage, or 30 individuals per plant after 1 week of damage during the booting stage. However, after 3-4 weeks of damage, the leaf spectral reflectance had stable bands and was significantly correlated with WBPH population size. At 440 and 680 nm, the reflectance of single and whole leaves at the tillering stage was sufficient to distinguish a population size of 16 WBPHs per plant damaged over 3 weeks, and at 680 and 760 nm, the reflectance was sufficient to distinguish 12 WBPHs per plant after 4 weeks of damage. The reflectance of all leaves at 680 and 760 nm during the booting stage was sufficient to detect 30 WBPHs per plant after 3 weeks of damage, while the reflectance of the 4LFT at 760 nm could detect 12 WBPHs per plant after 4 weeks of damage. In rice plants damaged by WBPH during the tillering and booting stages for 3 and 4 weeks, there was a significant correlation between the spectral bands and the difference vegetation index (DVI), ratio vegetation index (RVI), and normalized vegetation index (NDVI) of the 4LFT single leaf in the spectral range of 400-1 000 nm. Additionally, the WBPH population size remained relatively stable, showing a stronger correlation with DVI than with RVI and NDVI. Stepwise regression models were established to monitor WBPH population size during the tillering and booting stages of rice plants damaged for 3 and 4 weeks, based on the DVI of the 4LFT. The root mean square error of these models was approximately 4 and between 5-8 WBPHs/plant for the tillering and booting stages, respectively. [Conclusion]  The ability of rice leaf spectral reflectance to determine WBPH population size is affected by the growth stage of rice and the duration of WBPH damage. After two weeks of WBPH damage, there was a significant correlation between the spectral reflectance of both the 4LFT single leaf and all leaves and WBPH population size in the stable band regions. The DVI of leaf spectra shows a stable correlation with WBPH population size, which can be used to establish a pest monitoring model.