【摘要】 进行流体的相平衡研究，相图是一类有效的方法，但相图的实际确定过程常常面临实验难以准确进行的问题，而可靠的理论预测，是对实验研究的重要补充。文章介绍了积分方程理论(IET)的由来和研究简单流体相平衡的IET的几个特点，综述了叠加近似理论、Lennard-Jones流体经典模型、桥函数模型、萨基索夫闭包法、超网状链法、平均球面近似结构理论、Percus-Yevick理论、改进超网状链理论、自洽Ornstein-Zernike近似(SCOZA)理论等IET的研究与发展历程。研究表明，SCOZA理论与等级参照理论结合的进一步发展在未来很有潜力。更多还原

【Abstract】 Phase diagram is an effective method to study the phase equilibrium of fluids, but the actual determination process of phase diagram often faces the problem that it is difficult to carry out experiments accurately. Reliable theoretical prediction is an important supplement to experimental research. This paper introduces the origin of integral equation theory(IET) and several characteristics of IET for studying phase equilibrium of simple fluids, and summarizes the research and development history of IET, such as superposition approximation theory, Lennard Jones fluid classical model, bridge function model, Sarkisov closure method, super mesh chain method, average spherical approximate structure theory, Percus Yevick theory, improved super mesh chain theory, self consistent Ornstein Zernike approximation(SCOZA) theory. The research shows that the further development of the combination of SCOZA theory and hierarchical reference theory has great potential in the future.更多还原