从可靠指标β的本质意义出发，揭示了极限状态非线性引起的误差性质，证明了这种误差非统计意义的结论，提出了判别这种误差性质的一种数学方法，并给出了算例．分析表明，功能函数非线性对结构可靠度计算结果有时影响显著，当其非线性性质为凹向高斯空间的原点时，将偏于不安全． Starting from the essential significance of the reliability index β, the error nature caused by the nonlinearity of the limit state is revealed, the conclusion that the error is not statistically significant is proved, and a mathematical method to discriminate this error property is proposed, and an example is given. . The analysis shows that the nonlinearity of the function function sometimes has a significant effect on the calculation result of the structural reliability. When the nonlinear property is the origin of the concave Gaussian space, it will be unsafe.