中文摘要：

在项目的经济评价中，净现值（NPV）和内部收益率（IRR）是主要的两个指标，当用概率形式表示项目经济受到的风险时，如何给出NPV和IRR两者之间的风险传递关系是一个难题。本文通过研究NPV和折现率之间的函数单调性关系，得出NPV和IRR之间的风险概率传递解析关系，由此可以根据NPV的概率得到相应的IRR概率分布曲线。该方法能够提供更为全面的且更符合客观实际情况的经济评价决策信息，使项目经济评价更具科学性。

英文摘要：

Net present value（NPV） and internal rate of return are two main indexes in the economic evaluation of projects. When the probability is used to express the risk of projects, it is a difficult problem how to give the risk transmisson relationship between NPV and IRR. This paper studies the function monotonieity between NPV and discount rate. Then the analytic risk probability transmission relationship between NPV and internal rate of return（IRR）is deducted. According to the inferences, the probability distribution of IRR can be acquired from the probability distribution of NPV. The method can provide more comprehensive economic evaluation decision information, which makes project evaluation more seientifieity.