Other than the reflectance comparing to natural vegetation

various types of crop have their own representative phenological calendar features.This dramatic change of crops along seasons makes a great difference to the regular order changes of natural vegetation.MODIS-VI time series become the best indicator for these phonological features.In this paper

a new crop area index

called Pan-CPI

is proposed to reflect the quantitative functional relationship between the MODIS-EVI time series and crop planted area.The research region is located at Tongzhou

Beijing and its surrounding areas.The winter wheat planted area was determined by the key parameters of the Pan-CPI model from the samples collected by TM images and MODIS-EVI time series.The results demonstrated that:（1） The Pan-CPI model can well monitor the goal crop area and provide a new method for crop area estimation based on MODIS-EVI time series.（2） Accuracy analysis shows that:As long as the population of samples meet the requirement of model calculation（for example:5%）

the Pan-CPI model has a high stability to get a high consistency between multiple measurements and will not be influenced by different samples.While the size of stats window is 6×6 MODIS pixels

the multiple correlation coefficient（R 2） reach above 0.85.Compared with the result of TM

the Overall Windows Accuracy stabilizes at around 95%

Total Quantity Accuracy stabilizes above 92% and Post-Adjusted Total Quantity Accuracy reaches up to 96%.（3） For the area with complex

fragmental cultivation structure

the Pan-CPI model can provide a more reasonable crop area estimation than those results fromTM

which may easily be influenced by the loss of images in key phenology phases.