借助计算机模拟研究了应力台阶d与疲劳强度标准偏差σ的比d/σ、应力台阶数i及试样数量N对升降法测试疲劳强度均值μ和标准偏差σ的影响。结果表明：升降法测试疲劳强度均值的可靠度高于测试标准偏差的，同一试验条件下进行多次重复测试可以提高试验结果的可靠度。d/σ>3时，升降图难以满足D>0.3。标准偏差估计值σ的均值和标准偏差均与升降图应力台阶数i相关，升降法试验中应保证i为3或4。提高试样数量可以减小（μ，σ）的估计值（μ，σ）的分散性。

The effects of the ratio d/σ of the stress step d to the standard deviation of fatigue strength σ, the number of stress steps i and the number of sample N on the average μ and standard deviation σ of fatigue strength measured by up-and-down method were studied through computer simulation. The results show that the reliability of fatigue strength average measured by up-and-down method is higher than that of standard deviation, and the reliability of test results can be improved by repeated measurements under the same test conditions. When d/σ>3, it is difficult for up-and-down picture to meet the requirement of D>0.3. The average and standard deviation of the estimated value of standard deviation σ are related to the number of stress steps i in up-and-down picture, and i should be 3 or 4 in up-and-down method test. It is useful to reduce the dispersion of estimated value (μ,σ) of (μ,σ) by increasing the number of specimens.