This study analyzes the influence of ethanol as gasoline blend on a spark ignition engine and a mathematical tool is proposed based on multi attribute decision making approach to select optimal combination of operating parameters of a variable compression ratio multi fuel engine considering objective, subjective and integrated weights of attributes. Test fuels used were ethanol-gasoline blends having ethanol in proportions of 10, 20, 30 and 40 vol %. The compression ratio was varied as 6, 7, 8 and 9. The load was varied as 25, 50, 75 and 100%. A series of 16 experiments were conducted by adopting Taguchi based design of experiments resulting in L16 orthogonal array. The result of proposed method shows that the combination of compression ratio 6, ethanol-gasoline blend 30 vol% at a load of 75% is found to the best choice from among other trails and was validated using graph theory matrix approach