The isomorphism of public weather service is out of the public, policy makers, professional weather services, but the isomorphism is not be paid enough attention.Consequently, the public meteorological service is unable to meet the needs of multiple time space scales, more content, and more manifestation online Web service, leading to the difficulties in the docking of inter provincial systems and the integrating of local systems (province , county , or city level) into the national system. Taking category theory as a guide, the isomorphic model for four dimensional meteorological Web service, a system based on software reuse, is established, in an attempt to achieve the goals of “full coverage”, “uniform platform,” and “easy to promote.” Based on the specifications of the national public weather service classification, the four dimensional meteorological service containing time, space, content, and manifestation is obtained through scale quantification and, then introduction of the database adjacency model, seed fill algorithm, meteorological geographical information systems, knowledge management systems, and meteorological content management system, Google Maps software, service oriented architecture, etc., which act on the various objects within the four dimensions. Currently, the systems can provide Web online services to the public, policy makers, and professionals for 203 meteorological Web sites.