Biomass of agricultural waste is one of the major sources of fuel in our country. Thus, to increase the calorific value of biomass briquetting is done. In this study, cashew nut shells, rice husk and dry dung were used as raw material to produce a biomass briquette fuel. Waste flour was used as a binding agent for this briquette fuel. For making this briquette fuel, different proportion of all the three raw materials was experimented. Total twenty samples having different composition of all the raw material has been prepared and experimented. For all the twenty samples physical and thermal properties was determined. Bulk density, shatter index, resistance to water, durability index, compressive strength and calorific values are the physical and thermal properties which were tested in this study. It was found that the briquetting sample containing 55% cashew nut shell, 8% rice husk char, 27% dry dung and 10% waste flour has optimal values of physical and thermal properties by using Design expert version. Thus, this composition of carbonized cashew nut shell, carbonized rice husk and dry dung is best for briquetting biomass fuel.