In order to evaluate the photoperiod sensitivity of foxtail millet cultivars, here we investigated nine agronomic traits of 156 cultivars in two calendar years under two ecological areas with different photoperiod conditions. By deployment of photoperiod relative sensitivity comparsion analysis and photoperiod sensitivity comprehensive index D, we evaluated nine agronomic traits that associated with the photoperiod. The large phenotypic variations were observed (spikelet number > heading stage > panicle length > plant height > number of leaves > grain weight per panicle). The formula to calculate the light sensitivity comprehensive index D was D = -8.803×10-18 + 0.187X1 + 0.041X2 + 0.146X3 + 0.202X4 + 0.130X5 + 0.081X6 + 0.098X7 - 0.086X8 + 0.126X9, where X1, X2, X3, X4, X5, X6, X7, X8 and X9 represented heading stage, grain weight per panicle, plant height, number of leaves, panicle length, panicle diameter, spikelet number, grain number per spikelet and 1000-grain weight, respectively. The D values of spikelet number, panicle length, heading stage and grain weight per panicle number of leaves and plant height were 0.395, 0.239, 0.228, 0.176, 0.164 and 0.144, respectively. Taken together, this result suggested that spikelet number, panicle length and heading stage were strongly photoperiod sensitive indices, while number of leaves showed moderate photoperiod sensitivity, both of which could serve as indexs for evaluating foxtail millet photoperiod sensitivity. Due to the large variation on plant height and grain weight per panicle, both traits might be not considered to be deployed in photoperiod sensitivity evaulation in foxtail millet.