本文使用重要性抽样 (IS)方法 ,对数字光纤通信链路的误码率参量进行了估计 .并且 ,在设计IS偏置方案时采用了LDT技术 ,即把最优的LDT的α 扭转 (指数扭转 )密度选取为IS偏置密度 .计算机模拟实验表明 ,这种基于LDT技术的IS方法具有很高的精确度和计算效率以及充分的可靠性 ,特别适合于极低误码率的估计 .此方法为数字光纤通信链路的计算机辅助建模、分析和设计 (CAMAD)提供了一种有用的研究工具 . In this paper, the importance sampling (IS) method is used to estimate the bit error rate of the digital optical fiber communication link, and the LDT technique is adopted in the design of the IS bias scheme, ie, the α-twist of the optimal LDT Twisted) density is selected as IS bias density.Computer simulation experiments show that this LD method based on the IS method with high accuracy and computational efficiency and sufficient reliability, especially suitable for very low bit error rate estimation.This Method provides a useful research tool for computer-aided modeling, analysis and design (CAMAD) of digital optical fiber communication links.