Climate change is very likely to affect food security at the global, regional, and local level. An attempt has been made to study the impact of climate change on crop production and productivity of different crops in Banka district of Bihar state by observing some local condition and by using some data available from district agriculture department. Climate change can disrupt food availability, reduce access to food, and affect food quality and impact the production and quality of vegetables and legumes. Nutritionally important vegetables and legumes can be particularly sensitive to temperature increases and more vulnerable to heat stress than staple or cereal crops. By observing the last five years rainfall data, it was observed that the annual average rainfall of the district was 1182.1mm, 822.2mm, 1031.8mm, 910.3mm and 816.07 mm against the average normal rainfall i.e. 1156.3 in the year 2014, 2015, 2016, 2017 and 2018 respectively. In the year 2014, a negative deviation found (-2%), afterward, 29%, 11%, 21% and 29% deviation observed in the rest of the years respectively which indicates the more uncertainty of monsoon rainfall. By observing the 19 years rainfall data, it is clearly shown that the annual rainfall trend for the district are coming out to be significant at five percent level of significance and showing a decreasing trend of annual rainfall. The main reason behind this changing rainfall pattern was climate change. So, main emphasis should be given on the farming according to weather condition of those particular areas or region.