The rice hardness is one of the most important qualification to scale the rice quality. Nowadays the rice taste meter is employed to detect the rice eating quality, which is NIR-based to beget the controversy about precision. In virtue of the measurement of engineering theory, the design of the automatic measurement of the rice hardness was carried out. The experiments prove that the instrument can detect the rice hardness accurately, with the result consistent with that of the rice taste meter. The simple, accuracy and reliable method has the value of application for the measurement and estimates of the quality of the rice.