A detailed introduction to the requirements of a display and analysis system of rain gauge data is made. Based on the objective analysis of the advantages and disadvantages of the existing widely used methods, a software system applying the ISAPI (Internet Service Application Programming Interface) technology is devised, which consists of data query, vector graph drawing, objective inter pretation, contour drawing, etc., schemes within the framework of server/browser. The key techniques, such as vector graph drawing and rainfall map drawing for a river basin, are also discussed. Being independent of other software, it is easy to upgrade and extend.