NIOS II 软核处理器是Altera 公司一款灵活高效的嵌入式处理器，常应用于控制和通信领域。循环冗余校验（CRC）广泛应用于各种数据校验中。本文通过NIOS II 的自定义指令，成功地将循环冗余校验并行算法在FPGA 上实现。结果表明，加快了专项任务的执行，提高了系统的效率。关键词：循环冗余校验；可编程片上系统；NIOS Ⅱ；嵌入式系统；自定义指令Abstract: Nios II embedded processor is a general-purpose RISC processor core, and is widely used in the field of control and communications. The Cyclic Redundancy Check (CRC) is widely applied in data check. The paper described the implement scheme of CRC parallelalgorithmic in Nios II system. The algorithmic was successfully carried out in FPGA through the user-defined custom instructions and made the system efficiency improved.Keyword: Cyclic Redundancy Check; SOPC; NIOSⅡ; embedded system; user-defined custominstructions