Rapid acquisition of crop growth status information is essential for timely guidance of agricultural production. Based on the response mechanism of crop physiological and biochemical spectroscopy, a portable crop chlorophyll detection device based on ambient light correction was designed. The device measured reflectance spectral and ambient light spectral data with 20nm bandwidth centered at 610nm, 680nm, 730nm, 760nm, 810nm, and 860nm to calculate vegetation index and predict plant chlorophyll content. The features of the device were the supplemental light when the ambient light intensity was poor and the correction of the ambient light intensity under the supplemental light condition. To evaluate the sensor performance, the sensor was tested and calibrated. Experiments showed that the maximum difference in GPS positioning was 6.2m in latitude and 4.9m in longitude;the correlation between the light intensity response of the six bands of the spectral sensors and the measured values of the illuminance meter exceeded 0.99;the matching coefficients of the two spectral sensors were calibrated to 0.743 and 1.035 in the 610nm and 860nm bands, respectively. A fitting model between the supplemental light intensity and the measurement distance in the 610nm and 860nm bands was established for light environment correction;chlorophyll gradient experiments were conducted using nonwoven fabrics, and a mathematical model of NDVI vegetation index and plant chlorophyll content was established, with a model R2 of 0.685 under poor light environment conditions without supplemental light and a model R2 of 0.965 under supplemental light and with correction.