讨论了软件无线电接收机中数字下变频处理技术中的CIC抽取滤波器结构原理，分析了CIC滤波器级联ISOP滤波器进行抽取滤波的设计技术。验证了ISOP滤波器对CIC滤波器带内衰减补偿的有效性；采用了CIC抽取滤波器的系统，有效地缩减了窄带FIR滤波器阶数。This paper discusses the theory of CIC decimation filter in digital downconversion processing technique of software radio receiver and analyzed the design technique of CIC filter Cascaded ISOP filters which process decimation filtering. The results validate that ISOP filter can effectively reduce the passband droop caused by CIC filtering with little degradation in aliasing attenuation sand that CIC decimation filter system can largely reduce narrowband FIR filter’s lap.