由非离子型表面活性剂、助表面活性剂（醇）、水和油形成微乳液，用拟三角相图中微乳区的面积确定形成微乳液的最佳条件．实验证明，油的碳原子数加上醇的碳原子数等于表面活性剂的碳原子数时为微乳液形成最佳条件，也符合ＢＳＯ规律 The microemulsion was formed by nonionic surfactant, cosurfactant (alcohol), water and oil, and the optimum conditions for the formation of microemulsion were determined by the area of ​​microemulsion in pseudo - triangular phase diagram. Experiments show that the number of carbon atoms in the oil plus the number of carbon atoms equal to the number of carbon atoms in the surfactant is the best condition for the formation of microemulsion and also complies with BSO law