正形置换具有良好的密码学性质，可用于分组密码的设计以抵抗密码分析。正形置换目前还没有成熟的构造方法。本文从正形拉丁方截集的角度出发，通过正形拉丁方的增长实现了由n-bit正形置换生成(n+1)-bit正形置换的构造过程。该方法能够迭代产生大量的非线性正形置换，而且算法形式简洁，可用于动态产生正形置换。本文的结果提供了一个研究正形置换结构和构造方法的新思路。

Due to that orthomorphisms have good cryptographic properties, they play an important role in cryptography for resisting cryptanalysis. A new method is presented to construct an (n+1)-bit orthomorphism from an n-bit one where n>1. First, details of the method are provided and discussed. Then a simple example is presented to show how a 2-bit orthomorphism is expanded, rearranged, and selected to form a 3-bit one. Some experimental data are analyzed to demonstrate the efficiency of the construction. The method is not only a new way to construct orthomorphisms but also a new attempt of research in orthomorphism structure for building a relationship between n-bit orthomorphisms and (n+1)-bit ones.