Virtual plant simulation system design is the agricultural informatization and digital image processing combination. This paper first on plant leaf classification and image processing technology and method are discussed. Then introduce the classical edge detection methods, through different methods of theoretical analysis and simulation calculation are compared with each other, and their respective advantages and disadvantages and applicability, according to the Laplace edge detection operator, design and implementation of plant leaf shape recognition and detection system. The Laplace edge detection operator to complete the plant leaf shape recognition and detection, the two-dimensional geometric morphological modeling with data replication and expression of function. And agricultural information technology integration, by processing the image data more accurate recognition and detection of different kinds of leaf form, for the development of agricultural engineering to provide more effective, accurate data.