反证法作为解决中学数学竞赛问题一种常用方法,有重要研究价值,本文首先介绍反证法的概念,然后研究了反证法在中学数学竞赛中的运用,这部分主要引入历年数学竞赛中的典型例题,并对它进行深入研究,让我们不仅了解何时用反证法,如何做反证法中的优化假设,还掌握了反证中的局部反证. As a commonly used method to solve the mathematics competition in middle school, evidence-based method has important research value. This paper first introduces the concept of inverse proof, and then studies the application of inverse proof in the mathematics contest of middle school. This part mainly introduces typical examples in mathematical competition over the years. It conducts in-depth studies so that we not only understand when to use the law of negative evidence, how to make the assumptions in the law of proof, but also grasp the local evidence of counter-evidence.