Abstract: CAgMSS is an agrometeorological operational service system for users in national and provincial level operational units in China. It fully covers the monitoring, assessment and prediction of agrometeorological operational service, packing 10 main functions such as agrometeorological data analyzing, product processing, meteorological condition assessment, crop yield forecast, disaster degree assessment, agricultural pest meteorological condition prediction, agricultural weather forecast, ecological meteorological assessment, agricultural remote sensing, and crop model simulation. Modern information technologies are applied to realize the whole process such as data collection and management, professional model operation, products processing and distribution. The system realizes normalized management and high efficiency analysis of agrometeorological data based on large-scale relational database technology. It's also highly integrated based on plugin technology and can be used for spatial analysis and high quality rendering of agrometeorological data and product. The system integrates agrometeorological statistics, remote sensing and crop model technology, realizing comprehensive application of multiple data, multiple indicators, and multiple models in crop growth condition assessment. Crop yield meteorological forecast, agrometeorological disaster monitoring and agricultural weather forecast can also be done with high level of quantification, refinement and objectification.CAgMSS has been in use since 2012, and obviously improves the efficiency of agrometeorological operational service work, providing important support for refined and automation of agrometeorological product. Based on the system, a batch of high quality products such as agrometeorological condition assessment, crop yield forecast, foreign agrometeorological condition monitoring, key crop phenology and agricultural activity period meteorological service, agrometeorological disaster assessment are produced and provide important references for guiding the agriculture production and meteorological disaster prevention and reduction. The system is also applied to winter wheat in 14 provinces in 2012. By the year of 2018, some subsystems such as drought monitoring, crop yield forecast and crop model are used in 31 provincial meteorological bureaus.