Abstract: Based on the data of the grain crop yields per unit area from 1951 to 2004 in Henan Province,the change characteristic of the climate yields at multi-time scale was analyzed by using the wavelet analysis method.The results indicated that the grain crop yield per unit area showed an increasing tendency generally,but the fluctuation of the climate yield per unit area enlarged.The change period of the climate yield per unit area was roughly consistent with the historic drought and flood evolvement in Henan Province.The change of the climate yield per unit area showed two to four years and 20 years periods,but dominated by a two years period.

Key words: Grain crop yield per unit area, Grain crop yield per unit area, Climate yield per unit area, Drought and flood disaster, Wavelet analysis