This paper ffrst analyzes the changing pattern of temperature and precipitation and then constructs a Denitriffcation-Decomposition (DNDC) model to better understand the climate change impact on crop yields in Bangladesh. In the DNDC model, historical daily precipitation and temperature data used for baseline scenario and projected data have been taken from general circulation model (GCM). Different general circulation models (GCM) have been employed to analyze and estimate future temperatures and precipitations. The result of the general circulation model (GCM) study ffnds that the overall temperature in Bangladesh tends to increase by 1.5 0C and 2.8 0 C in the years 2030 and 2050. Precipitation patterns are also projected to increase in 2030 and 2050. The result from the Denitriffcation-Decomposition (DNDC) model ffnds that overall rice, corn, winter wheat, potato, vegetable, and pulses yields decrease both in 2030 and 2050, and decrease more rapidly in 2050. In the year 2050, the output of rice, potatoes, and pulses falls by -33%, -35%, and -54%, respectively, while the production of corn and wheat falls by -22% collectively. Since rice is the main food consumed in Bangladesh, a decline in rice output will pose a serious threat to the country's ability to feed itself.