As the most intuitionist and effective way to study the basic character of flowage, flow visualization has wide foreground in many engineering fields. With the development of computer technology, optical technology and image processing technique, Particle Image Velocimetry(PIV) appears and becomes to an important part in the application of flow visualization. The Image Processing technology is the key for flow Visualization to obtain the information of the flow field. The application of Image Mosaics based on Genetic Algorithm is studied in this paper, which can provide a good technique condition for the development of flow visualization.