本文基于数字信号处理中信号经过多次叠加平均后，信号中的随机噪声将被消除的原理，设计了一种针对周期性信号的随机噪声消除电路。该电路主要由锁相倍频、周期延时及放大电路组成。本文对该电路的原理进行分析，并通过实验对包含有较大随机干扰的周期性信号进行处理，得到了消除各种随机干扰的检测信号。该电路目前已成功用于EAS系统中的随机干扰信号的消除。 　　Abstract: 　　Based on the theory that the random noise of digital signal will be eliminated after multiple stacking average， this article designed a random noise elimination circuit aiming at periodic signals. The circuit was mainly consisted of phase-locked frequency circuit， cycle delay circuit and amplifying circuit. This paper analyzed the theory of the circuit， processed periodic signal that contained a large random interruptions in the experiment， and got detection signal which could eliminate all kinds of random interruptions. The circuit has been successfully used in EAS system to eliminate the random interruptions signal.