本文研究薄层流中出现的一类三阶奇摄动数学模型．本文不采用研究其渐近等价的二阶奇摄动微分方程的方法,而利用边界层函数法,直接讨论该数学模型的渐近解,并严格地证明了解的存在唯一性和其渐近解的一致有效性．本文的结果不仅去掉了以往方法所必须的位势条件,纠正了某个不适定的假设,而且推广了以往的结果． This paper studies a class of third-order singular perturbation mathematical models that appear in the laminar flow. This paper does not adopt the method of studying the asymptotic equivalent second-order singularly perturbed differential equations. By using the boundary layer function method, the asymptotic solution of the mathematical model is directly discussed and the existence and uniqueness of the solution and its asymptotics Uniform validity of solution. The results of this paper not only eliminate the necessary conditions for the previous methods, correct some ill-posed assumptions, but also generalize the previous results.