Investigating the impact of Gasoline fuel on diesel engine performance and emission is very important for military heavy- duty combat vehicles. Gasoline has great potential as alternative fuel due to rapid depletion of petroleum reserves and stringent emission legislations, under multi fuel strategy program for military heavy- duty combat vehicle. There is a known torque, horsepower and fuel economy penalty associated with the operation of a diesel engine with Gasoline fuel. On the other hand, experimental studies have suggested that Gasoline fuel has the potential for lowering exhaust emissions, especially NOx, CO, CO2, HC and particulate matter as compared to diesel fuel. Recent emission legislations also restrict the total number of nano particles emitted in addition to particulate matter, which has adverse health impact. In this research study, the effect of using Gasoline fuel was evaluated, in a heavy- duty diesel engine, for performance, combustion and emissions of CO, CO2, UHC, NOx, along with smoke opacity, including particle size-numbers distribution characteristics. These were compared for Gasoline and diesel fuels by applying EGR with turbo charging at different load condition, in a 12- cylinders, 720 kW, 38.8 liters CIDI military heavy- duty diesel engine. The experimental test results showed that engine performance with Gasoline fuel, was slightly lower than with diesel fuel. Gasoline fuel, with 5 % EGR rate, has produced lower exhaust emissions including 32 % lower NOx emission along with lower nano particles emission, as compared to diesel fuel with 0 % EGR rate at different load condition.