An experimental work was carried out to investigate the effect of the double swirl on the combustion performance of a Diesel fuel spray in a confined chamber. Eight combinations of double swirl arrangements were examined. The flame thermal and chemical structures were studied on the comparative basis. The combustion efficiency was calculated based on the exhaust gas species concentrations. The results indicated that the optimum flame performance as achieved with the co-swirl mode when the inner air stream is swirled at 60o while the outer air stream is swirled at 45o. This is attributed to providing a significant swirl strength around the fuel injector and a simultaneous flow shearing effect via the swirl angle difference between the two streams. In most of the counter-swirl flow combination, the excessive flow strain produced by the high relative swirl angles was found to produce local flame extinction and deterioration in the combustion efficiency.