The study was conducted with the purpose of understanding the effects of climate on cropping system of the district of Thach That, Hanoin during 2000-2010 period. Hydro-meteorological data and statistical information related natural and social-economic conditions as well as cropping patterns were gathered and analyzed. In addition, multiple cropping model was implemented to compare with the traditional monocropping system. Crop diversity coefficient was calculated using Shannon's formula. It was found that the climate and weather conditions during 2000-2010 period in Thach That district showed unusual occurrences as evidenced by lower mean temperature (23.8°C) and unusual high rainfall in October (537mm) in 2008 or no rain in July 2010.. Abnormal changes in temperature and rainfall had affected cropping area and the kinds of crops grown leading to changing cropping structure and loweringbiodiversity coefficient. As a result, the coefficient of biodiversity in 2008 was lowest (0.34) during 10 years period. In response to abnormal weather conditions, diversifying crops and cropping structure are suggested as solutions to achieve stable yield and economic efficiency.