To enhance the stability as well as accuracy of near-infrared rapid nondestructive testing, this paper compares the spectral effects of three different types of light sources in the conditions of fiber optic light source, halogen cup light source and ring light source, and the results show that the ring light source has the lowest spectral noise, moderate irradiation intensity and the best uniformity. Based on these studies, the power of the light source, the distance from the optical source to the potato surface, and the distance from the optical fiber to the detection point on the potato surface are investigated in this study. The spectral model’s prediction effect on potatoes’ soluble solids content under different factors was evaluated by a three-factor, three-level response surface test. The optimal parameters were light source power 238.33 W, distance from fiber optic probe to sample surface 8.17 mm, distance from the light source to sample surface 370 mm, RP=0.867, and RMSEP=0.149°Brix of the PLSR model for soluble solids prediction. To further eliminate equipment and environmental noise, interference of noise was reduced by different preprocessing algorithms. The outcome showed that the algorithm with the standard variable ranking approach had the best noise removal effect, with RP=0.914 and RMSEP=0.132°Brix, which obtained a better prediction result while effectively removing noise. The test results show that optimizing the testing environment and conditions through response surface testing can effectively improve the prediction accuracy of potato quality testing and provide technical guidance for the construction and device selection of near-infrared online the nondestructive detection environment for potatoes.