基于一维均相平衡模型，导出系统无量纲特征方程，采用频域分析方法，开发了一个通用性程序，研究两相自然循环中流动不稳定特性。程序能直接求解自然循环回路的无量纲稳定边界，计算结果与所得到的实验数据吻合良好，并讨论了各参数对系统稳定性的影响。 Based on the one-dimensional homogeneous equilibrium model, the dimensionless characteristic equation of the system is derived and a generalized procedure is developed by using the method of frequency domain analysis to study the instability characteristics of two-phase natural circulation. The program can directly solve the dimensionless stable boundary of the natural circulation loop. The calculated results are in good agreement with the experimental data obtained and the influence of each parameter on the system stability is discussed.