The invention discloses an image-based automatic identification method for drought stress on corn at an earlier growth stage. The method comprises: step one, preparing earlier-growth-stage corn plant image sample sets on different drought stress conditions; to be specific, acquiring a plurality of earlier-growth-stage corn plant image samples on different drought stress conditions by using imaging equipment, carrying out segmentation on the sample images, carrying out feature extraction on the segmented target images to obtain feature vectors of the image samples, and recording drought types to which the image samples belong; step two, training a two-stage drought stress automatic identification model by using the obtained earlier-growth-stage corn plant image sample sets; and step three, carrying out automatic identification on the drought stress on the earlier-growth-stage corn image samples. With the method disclosed by the invention, automatic identification of the drought stress state of the earlier-growth-stage corn plant is realized; the agricultural drought disasters can be warned early and timely; and thus the corn plant and economic losses are reduced. And the effectiveness of the method is verified by the experiment.