在考虑到多种影响因素的情况下，得到了FWM(四波混频)噪声标准差的较为精确、高效的评估算法，该算法对优化设计密集波分复用系统具有重要意义。在忽略信道间串扰的基础上，利用动态分步傅里叶算法先行得到单信道内的脉冲传输规律，然后在此基础上精确求解决定FWM效率大小的重叠函数。实例计算结果表明：FWM效率大小与脉冲在传输过程中的变化有关，在群速度色散系数绝对值相对较小、归一化的特征宽度相对较大、入射脉冲峰值功率相对较大时，这种关联度比较大。啁啾系数为正，取值较大，且传输速率相对较高时，不能忽略脉冲随传输距离的变化对FWM效率的影响。

Taking into consideration of various influencing factors, it is of major significance to have an exact and computationally efficient evaluation algorithm for the variance of Four-Wave Mixing (FWM) noise to the optimal design of DWDM systems. On the basis of neglect of inter-channel crosstalk, this paper first obtains the pulse transmission law by using the dynamic split-step Fourier algorithm and then on this basis, obtains the channel overlap functions that determine the efficiency of FWM. Calculation results of examples show that FWM efficiency is to a certain extent related to the pulse variations in the course of propagation: when group-velocity dispersion coefficient is relatively small, the normalized characteristic width is relatively large and when the peak-power of the incident pulse is relatively large, the correlation degree is large, and that when the chirping coefficient is positive and large and the propagation rate is relatively high, the effects of pulse variations with the propagation distance on FWM efficiency cannot be neglected.