Wheat plant water content is one of factors that affects the feeding rate, separation loss and selection cleanliness of combine harvester. A rapid nondestructive detection method for wheat plant water content measurement was proposed based on near-infrared photoelectric sensor. In this system, the near-infrared detectors of different wavelength were designed and the system was built to sense the reflection intensity of wheat plant by the method of median filter and reference real-time correction. Multiple sets of samples were tested and analyzed, then multivariate linear regression, multivariate stepwise regression, partial least squares, and least squares support vector machines were used to build the model respectively. The results showed that the model based on least squares support vector machines performed best, whose correlation coefficient of the correction set came up to 0.9742. Other sets of samples were tested by the established mode, and found out that the correlation coefficient between the true and predicted value of wheat plant water content was 0.9337 and standard deviation of predictive sets were less than or equal to 3.00%. This paper provided a rapid and nondestructive detection method and equipment for wheat plant water content, which was beneficial to improve the work performance of combine harvester by real-timely adapting the operating parameters according to the wheat plant water content.