The invention relates to a construction method of a wheat 
powdery mildew illness monitoring model. The construction method comprises the steps of: obtaining 
winter wheat canopy original spectrum datain the main plane 
vertical angle and wheat 
powdery mildew illness index data under the stress of the 
powdery mildew, selecting a 
wavelength lambda1 and a 
wavelength lambda2 from wavebands with determination coefficients R<2> between a 
canopy spectrum index and a wheat powdery 
mildew illness index being not smaller than 0.5, and introducing a regulation parameter K and a 
reflectivity K*Rlambda3 corresponding to a 
wavelength lambda3 to construct a corrected specific value 
vegetation index as shown in the description. A wheat powdery 
mildew illness monitoring method adaptive to a wide angle comprises the steps of: obtaining 
reflectivity data when light with wavelengths of 744nm, 762nm and 710nm irradiates a 
winter wheat canopy under the stress of the powdery 
mildew within an angle range of 0-+30 degrees from the main plane to obtain a corresponding corrected specific value 
vegetation index as shown in the description. The construction method of a wheat powdery mildew illness monitoring model and the wheat powdery mildew illness monitoring method adaptive to a wide angle allow a wide monitoring angle when the wheat powdery mildew illness is monitored and are wide in applicability.