Abstract: 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 considered.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 result,several optimization schemes are given to meet different project demands.