工程网络计划的基础是对各工序持续时间的估计，而导致工序工期不确定性的因素不仅具有随机性，通常也具有模糊性。文章提出一种具有LR型模糊数的线性规划模型，解决了工程网络计划的时间参数 估计和关键路径识别问题，并通过引入λ截集来充分描述决策者在不同情形下对工序工期估计的可信程度。 最后给出一实例详细说明了该方法的应用过程及有效性。

Estimation of activity duration is a basic problem for project scheduling. However, the uncertainty of activity duration originates from both probability and fuzziness in the real world. This paper develops a linear programming method with LR type fuzzy numbers, which aims to estimate activity duration and identify critical path, and applies the λ - cut to indicate the degree of optimism of a decision maker. Finally, an example is given to demonstrate the application and validity of the proposed method.