The polynomial expression model is a new model to interpret the light scattering process inside leaf/soil system and decipher the non-linear relationship between component spectra and canopy reflectance.It uses high order polynomial to interpret the scattering process inside canopy

and each coefficient of the polynomial expression represents the possibility with which the incident light

after multi-scattering of the components

goes out of the canopy and enters the sensor.This value depends on the canopy structure including crop cover rate

leaf distribution etc.So the polynomial model has the capability to invert the canopy structural parameters.This study is designed to invert the crop cover rate using this model.Firstly the canopy reflectance model SAILH is used to simulate BRDF spectra and the corresponding cover rates.Then the relationship between the polynomial coefficients from the polynomial expression model and cover rates is built.Finally

an experiment is designed to validate the model inversion.