中文摘要：

提出了一种针对容错系统的新的评估策略。考虑到系统的性能、时间及成本等三组质量因子，并通过这三组因子计算出系统的综合质量指标。运用该评估策略，可比较由不同容错组件组成的容错系统的质量特性，并根据所获得的评估结果帮助优化当前系统。另外，为达到符合质量要求的较优结果，还给出了对不同需求情况下的优化方案。

英文摘要：

Software fault tolerance technique is used to ensure high reliability. In order to evaluate the quality of fault-tolerant systems, expected execution time and cost must be con sidered. A new evaluation strategy is proposed to evaluate, evaluating the system with three groups of quality factors, which is the capability, the time and the cost. By using them, the system＇s integrative quality factor can be calculated. When applying this strategy, we compare the quality of software systems which is consist of different fault-tolerant components. The results can be used to improve fault-tolerant system. To achieve the required optimal re suit, several optimization schemes are given to meet different project demands.