The quality of soybean oil can be judged according to its grade. Generally speaking, soybean oil is divided into primary, secondary and tertiary. First-class soybean oil has the best quality, transparent color, pure taste and high nutritional value. The quality of secondary soybean oil is second, the color is slightly turbid and the taste is slightly impurity. The third-grade soybean oil has the worst quality, turbid color and heavy taste. So first-class soybean oil is the best choice.