Abstract: In the paper, at different growth stages of summer maize, canopy reflectance spectra were measured, and then canopy spectral reflectance characteristics were compared and analyzed synthetically in 2005 and 2006 among different conditions, such as different space scales, different planting densities, different observation angles, different growth stages, different leaf area indexes (LAI), different nitrogenous (N) levels, different leaf water contents and different weed contents. In the end, the authors probed into the mechanisms of spectral reflectance characteristics above. The results of study indicated that under different conditions, canopy spectral reflectance characteristics of summer maize took on disciplinary change. At NIR (near-infrared bands), the reflectance gradually increased along with adding nitrogen, especially at 750～1350 nm, but reduced at visible light bands. The reflectance gradually decreased along with escalating the probe, but increased along with developing weed content. The results revealed the tremendous potential of capturing physical and chemical information about summer maize growing in the field using hyper-spectra remote sensing technology, at the same time, provided the basic on constructing retrieved model through remote sensing method in the future.