With the development of intelligent meteorological service, the demand for a mobile application to complement traditional weather forecast operational systems, whick are weak in timeliness and mobility, has been increasing. To address this issue, the Central Meteorological Observatory (CMO) Meteorological Decision-Making Service Mobile Application (abbreviated as Decision-Making Service App), which is implemented with the latest mobile Internet technologies and serves decision service directors and staff, has been developed. During the development process, a number of key technologies such as a rendering engine using WebGIS and OpenGL ES technology, user behavior analytics with big data, and high-level security have been innovated. Key functions including city weather forecast using refined smart grid, decision service products, realtime observations and statistical query, and early warnings have been developed. Ever since it is put into operation in daily weather forecast, assurance of national conferences and activities, and prevention and mitigation of natural disasters, Decision-Making Service App has helped to improve refined analysis and decision-making service of CMO and other meteorological observatories.