Relevant information on crops grown in a country is important for the national economy，particularly in forecasting agricultural production and for the grain trade．Crop-Specific information is collected mainly through surveys of standing crops in agricultural research stations and agri-meteorological stations．The method mainly consists of on-the-spot Visual assessment．However，the number of such stations is limited because of the high Cost of maintaining them．Also，Spatial variation in physico-chemical properties of soil and farming practices makes it difficult to extrapolate the data from one station to represent a larger area．Therefore，it is necessary to have a better method of co11ecting crop-specific information．
The past 40 years have seen commendable progress

in the use of remote sensing to monitor crops．Since the 1970s，remote sensing has made it possible to obtain quantitative crop-specific in formation on a regional scale：the China CropWatch System(CCWS) has been a success story．With about 20 years research experience behind it，the Institute of Remote Sensing Application(IRSA) of the Chinese Academy of Sciences(CAS) developed the system in 1998 and has operated it ever since．CCWS covers entire China and 46 major grain—growing countries of the world．The System monitors the condition of the growing crop，crop production，drought，crop plantation structure，and cropping index．After 10 years’ operation and improvement，CCWS began publishing，and currently publishes 7 monthly bulletins and 20 newsletters every year。Which have become important sources of information for government bodies including the State Council，Ministry of Agriculture Ministry of Commerce, State Grain Administration，and State Statistics Administration．CCWS consists of seven components，Which are as follows：crop growth monitoring，drought monitoring，grain production estimation，crop production predicting，crop planting structure inventory，cropping index monitoring，and grain supply-demand balance and early-warning(Figure 1)．As for the frequency and lengths of the periods covered，descriptions of different stages of crop growth and the extent and severity of drought are revised once in ten days；

cropping index(the number of times a given area is sown Within one year)is published yearly；data on the shares of different crops in total arable area sown (crop planting structure)are published quarterly；and estimates of area and production are published a month before the harvest and revised once after the harvest．The monitoring can be carried out on different Scales or levels ranging from a village and a county through a province and the whole country to the main producing countries in the world and the entire globe．
The accuracy of each monitored item in the entire content of CCWS is greater than 95％and the relative error between years is less than 1%, Which meets the users’ requirem-ents and expectations．CCWS system and information service can be customized for all kinds of users, whatever their need for crop-specific information may be.