Abstract: A client/server structured local area network(LAN) was set up in our chrornatography and mass spectrum laboratries at the end of 1995. It is composed of an HP 4930 ChemServer,twelve PCs connected with GC, LC, MS and other instruments, an HPLJ4 network printer and a DC 806 repeater.An HP 35900E dual channel interface can be easily connected into the LAN as needed.The operating system for the server is HP-UX 9.0, for client PCs is MS-DOS 6. 22 and Windows 3. 11. The compliance standars are TCP/IP and other industrial standards. Target 3 is a powerful data analysis sofware installed in the HP 9715 workstation which acts as the server. Beside the basic functions of a network, it has the following features: data acquisition and instrument control, data file review, chromatographic data analysis and mass spectra library search, management of other file, QA/QC, reporting, security and regulatory comliance, upgrade to laboratory inforrnation management system (LIMS). It has been used for analysing the water of Yantze River.