提出了一种码率码长灵活变化的准循环低密度奇偶校验(Quasi-Cyclic LowD ensity Parity Check,QC-LDPC)码,利用构造出的H矩阵可以达到较大的圈长(girth)值,并能在girth值不变的前提下实现码率码长的灵活变化。分析和仿真结果表明,利用该方法可以得到不同码率条件下码长灵活变化的可用码字,大大增加了高性能QC-LDPC码的可用数量。与WIMAX中IEEE802.16e标准中推荐的H矩阵进行比较,此类QC-LDPC码具有较好的优越性。 A Quasi-Cyclic Low Density Parity Check (QC-LDPC) code with a flexible code rate code length is proposed, and a large girth value can be achieved by using the constructed H matrix , And can realize the flexibility of code rate code length under the premise of girth value unchanged. The analysis and simulation results show that this method can be used to obtain the code word with flexible code length under different code rates, which greatly increases the available number of high performance QC-LDPC codes. Compared with the H matrix recommended in IEEE802.16e standard in WIMAX, such QC-LDPC codes have better advantages.