The effects of temperature (5~40 ℃), water content (10.14%~29.55%) and frequency (1~100 kHz) on quinoa capacitance were studied by LCR meter. Based on the multiple regression analysis method, and the optimal excitation frequency (21 kHz) and water content detection model for quinoa water content detection were determined. The minimum system board of MSP430F149 microcontroller, TFT touch-screen, AD5933 impedance measurement chip, self-made concentric circle capacitance sensor and DS18B20 digital temperature sensor were selected to complete the design of the quinoa moisture rapid detector. The accuracy test of the detector showed that the average relative error of quinoa water content test results was 4.17%, and the measurement time was less than 2 s. The performance of capacitive quinoa moisture rapid detector based on AD5933 is satisfactory.