本文主要介绍CCITT v.42bis建议的压缩算法的主要特点，以及实现该算法的数据结构，形成新串的方法，动态维护字典的方法和指针编码，并给出V.42bis建立的模拟结果。V.42压缩可以用于SNDCP子层分组数据部分的压缩。-This paper describes the main features recommended by the CCITT v.42bis compression algorithm, and the data structure of the algorithm, to form a new string method, the dynamic maintenance of the dictionary and the pointer encoding, and gives the V.42bis established simulation results. V.42 compression can be used for part of the SNDCP sublayer packet data compression.