Abstract: The purpose of building the monitor subsystem is to guarantee the safe operation of the National Meteorological Data Storage System (MDSS) and to guide the updating of the DMSS. As an infrastructure for sharing scientific meteorological data, real-time operation and post-standardization are supported by MDSS. According to their functions, all components of MDSS are divided into two groups. The supporting equipment includes hardware as well as their accessory software, and the operation of real-time database integrates the database and the data storage. In the equipment group, the targets vital for the smooth running of equipments are monitored, such as the CPU usage and the memory usage of services. Most of the objects monitored in the group of operation are time-series and sequence operation. For instance, the amounts of observed data are entered into the real-time database at a given time. The possibility of using the current monitor software is also considered, and their shortcomings are presented. The structure of the subsystem is divided into three modules:the collection module, the storage and the analysis module and display module. The monitored operation data are gathered repeatedly from the MDSS by the collection module.The gathered information is calculated by the storage and analysis module to confirm the state of the MDSS and the results are stored in the database and the service memory. The state of the MDSS is shown by the display module on the Web pages. A database scheme is designed as the communication channel between the collection module and the storage module. A tree shape program interface is designed for passing information between the modules of storage and display for users on different levels.Some special techniques which are keys for the implementation of the monitor subsystem are explained, such as the Java Stored Procedure. Experience and the following work of the subsystem are also discussed. The reliability and stability are demonstrated by the performance of the subsystem.