Abstract: Relying on weather forecast and climate prediction，a cotton meteorological service system based on functional-structural plant model Cotton XL was developed.Cotton XL has been designed and calibrated to simulate development of leaf and fruits（square，flower and boll），plant height and branching.Crop development in Cotton XL was driven by thermal time，population density，application of growth regulator mepiquat chloride and topping of main stem and branches.This model could simulate cotton fibre development in relation to temporal and spatial distribution of retained fruits.By inputting parameters of climate，soil，management and varieties，the system could set service on growth simulation，yield forecast，fiber quality prediction and meteorological disaster early warning.Based on B/S three-tier structure mode，this system included front-end display layer，data storage layer and background analysis layer.Inner call of Cotton XL and transfer of information between Cotton XL and database were carried out with Java.Transfer of information between front page and database was carried out with PHP.Database of climate，soil，management and cotton cultivars of Xinjiang cotton area were developed by using MySQL.The system accorded with TCP/IP agreements，which could be installed and ran in server，and be browsed on Internet.Establishment and application of the system could improve application ability of crop growth model on yield prediction，agro-meteorological disasters early warning and so on.It′s important and realizable to enhance meteorological service ability on agriculture.