Abstract: Based on 16 d MODIS NDVI synthetic time-series data in 2011 of 500 m space resolution and the plant distribution map of Zhengzhou area. The seasonal variation of vegetation in Zhengzhou, Henan Province was studied by using high quality vegetation index in MODIS data. The key phenophases of 3 vegetation types were extracted by time series harmonic analysis (HANTS) and sliding average method. Results showed that in 2011, most of forest land and grassland in Zhengzhou grew on the 85^th-110^th day, basically matured on the 220^th-240^th day, and gradually stopped growing on the 305^th-325^th day. The length of growth season mainly concentrated for 200-220 days. Most Triticum aestivum started growing on the 40^th-60^th day, reached the maximum on the 100^th-120^th day and ceased to grow on the 135^th-150^th day. The growth period of Zea mays was concentrated on the 165^th-180^th day. It matured on the 220^th-235^th day and ended the growth on the 260^th-270^th day. The length of crop growth season mainly existed for 90-110 days. The research results were consistent with field research and previous research data, which is reliable. Therefore, MODIS NDVI data can rapidly monitor plants and effectively obtain regional plant phenology information.