Cow milk, is a product of the mammary gland and soymilk is a creamy, milk-like product made by soaking and grinding soybeans in water. The present investigation was made to develop soy-fortified cow milk by partial addition of different levels of soymilk to cow milk T1, T2, T3, T4 and T5 and to determine physico-chemical properties of these blends. The physico-chemical properties i.e. fat, protein, acidity, ash, TSS, specific gravity, and pH of soy: cow milk in the ratio 100:00%, 75:25%, 50:50%, 25:75% and 00:100% was determined. The treatments T1, T2,T3, T4 and treatment T5 consist of 1.9 to 3.3% of fat; 3.1 to 3.3% of protein; 0.14 to 0.22% of acidity; 0.33 to 1.88% of ash; 6 to 10.7°B of TSS, 1.014 to 1.025 of specific gravity and 6.8 to7.3 of pH. The treatment T4 had best results for physico-chemical properties of soy: cow milk blend such as 2.75% fat, 3.10% protein, 0.15 % acidity, 0.50% ash, and 10.7°B TSS, 1.023 specific gravity and 7.26 pH respectively.