In order to find a new fast method for testing nitrate in plant, we developed reflectometry YN-FS to test. Through the tests of standard samples, recoveries of samples, and contrast experiment with standard method, our purpose is to verify the feasibility of this new method. When nitrate content was 1.0-50.0 μg/mL, the experimental results showed that the recovery rate of standard addition method was up to 92.8%-107.9%, and the relative standard deviation (RSD) reached 2.4%-4.6%. Also, the absolute error was less than 10%, there was highly significant positive correlation (r=0.999) between double wavelength reflection and nitric acid reduction method. Research found that using reflectometry based on double wavelength technology to test nitrate contents in a plant sample is stable and reliable.