Abstract: 【Objective】 The sequential cropping index of arable land is an important agricultural information, the objective of this paper is that monitor and analyze this parameter, and supply a reference for guiding agricultural production.【Method】Based on the MODIS (moderate resolution imagine spectroradimeter) vegetation data from NASA(National Aeronautic and Space Administration) in America and the actual land use map with a scale of 1﹕2 500 000, using two times differencing, this paper monitors the cropping index of arable land in Zhejiang Province from 2001 to 2004. 【Result】 Within one year, there are principles of the interaction between the time series of NDVI (normalized difference vegetation index) profile and the growing process of crops, this process can be described as planting, seeding, heading, ripe, harvest and so on, and the peak of the time series of NDVI profile indicates that the colony ground biomass reaches the tiptop, so sequential cropping index can deem that equal to the number of peaks of time series of NDVI profile. Based on this principle, the sequential cropping index of all cities in Zhejiang Province was worked out.【Conclusion】It was found that the sequential cropping index in southwest is bigger than northeast in Zhejiang Province in the space. In the time, the sequential cropping index shows the depressed levels from 2001 to 2003 and the value increaseed to some extent in 2004, but the value was low, so there are much potential for the sequential cropping index of arable land in Zhejiang Province in consideration of the geography and the climate in Zhejiang Province.

Key words: Sequential cropping index, MODIS-NDVI, Monitoring