A treatment recommending system of plant symptom includes an operation interface, an image capture unit, a processing unit and a storage unit for storing plant symptom data and diagnostic data. The processing unit may find target contour data presenting a plant part according to symptom description and symptom characteristic data. The image capture unit obtains plant image data corresponding to the target contour data. The processing unit analyzes the plant image data, and coordinates with the symptom characteristic data to determine corresponding treatment recommendation data.