摘要：换元法是中学数学中的一种常用解题方法，在中学教学中,中考、高考试卷中常出现应用换元法的题目，所以老师要求学生掌握并熟练应用换元法解题，因此换元法在中学数学应用中起着重要的作用.本文主要介绍换元法在因式分解、根式化简、代数恒等式证明、证明不等式、求函数的值域和极值题型中的应用及分析.但由于学生概念不清，在换元过程中往往会出现许多问题，所以本文还探讨了换元法应用时最为常见、最为重要的几个问题，以及如何解决这些问题.

关键词:换元法的基本概念；换元法的应用和方法技巧；换元法常见错误分析

Abstract:The substitution method is a common problem-solving approach in the Middle School Mathematics, in the middle school teaching, in senior high school entrance examination, examination papers, often appears in the application of substitution method, so the teacher asked the students to master and skilled application of substitution method solving, substitution plays an important role in middle school mathematics applications. This paper describes the substitution factoring, radical simplification of algebraic identities proved to prove the inequality, application and analysis of the demand function of range and extreme value kinds of questions. But the students clear about the concept in the substitution process often there will be many problems, this article also discusses the-for-element method application is the most common and most important, and how to solve these problems.

Key words:Basic concept of Substitution method; Application method and skill of Substitution method; Common error analysis of Substitution method