Under the experimental condition, the hyperspectral reflectance spectra of the mixed pixel of lotus and water body were acquired using the multi-angles dichotic reflex platform and ASD spectrum instrument. The reflectance spectral morphological character index variation of the hyperspectral mixed pixel at different component proportion was analyzed. The conclusions are as follows: the correlation between these morphological indexes was obvious, and the best morphological index was chosen by removing the index whose R2 was greater than 0.5 (R is correlation coefficient); the variation of different morphological index was obvious; the cluster analysis shows that there was a critical value in the progress of the transformation from the pure pixel (water) to mixed pixel. If the proportion was less than the critical value, the reflectance spectra reflected the reflection characteristics of pure pixel; otherwise, it was the reflection of characteristics of mixed pixel.