S-N曲线是用名义应力法预测结构疲劳寿命的基础。基于试验疲劳寿命分散的物理机制，提出了一个S-N曲线试验数据处理的加权最小二乘法，此方法中每组数据的权重与该组数据的置信区间成反比。计算结果表明用考虑置信区间长度影响的最小二乘法拟合得到的S-N曲线比用一般最小二乘法得到的S-N曲线具有更高的可靠度，给出的寿命预测结果也更安全。

The S-N curve is the base of calculating fatigue structural life. Founding on physical mechanism, this paper presents a weighted least square method in which the weigh of a group of test data is inversely proportional to the length of the confidence interval. The calculating results show that the S-N curve which is gained by the least square method considering the effect of length of the confidence interval is more reliable and secure than the S-N curve which is gained by general least square method.