Crop growth parameters are important data for describing crop growth and evaluating environmental conditions (including agrometeorological disasters) influencing crop growth, and also the important basis to predict crop yields and guide farm management. The research progresses and the application of automatic observation techniques for crop growth at home and abroad are discussed, focusing on plant heights, crop coverages, crop growth periods, and other characteristic parameters, and the principles, methods, feasibility and limitations of the related technologies are explored. The analysis shows that computer vision image processing technology, based on crop pictures from CCD sensors, can be used to obtain morphological characteristics, coverage, developmental stages, and leaves color of crops more accurately, fast, and visually, which is the basis of the verification of the crop growth conditions estimated by satellite remote sensing and the automatic monitoring of damages by diseases and insects on crops, as well as the supply of nutrients to crop, and shows good prospects.