由于城市地下燃气管网压力较低，环境噪声复杂，泄露信号微弱，使得泄漏信号难于用基于二阶累积量理论的信号处理手段检测到。根据高阶累积量及双谱理论，将双谱应用于高斯噪声下的非高斯信号检测，通过直接法得到双谱的估计值，并利用二维窗来提高双谱的频率分辨率，然后根据实际情况建立了相应的假设检验模型。实验结果表明，该方法可有效的检测出低压燃气管网的泄漏信号，检测距离不小于20m。

Due to low pressure，complex circumstance noise and weak leakage signal of the urban underground gas pipelinre，it was difficult to detect the signal by general signal processing method which is based on the second-order cumulants．According to higher-order cumulants and bispectrum theory，bispectrum was applied to non-Gaussian signal detection in Gaussian noise，the frequency resolution was improved in bispectrum through the direct method of bispectrum estimates and the use of two-dimensional window，setting up the corresponding hypothesis testing model in actual situation．Experimental results show that the method can be validated to detect leakage signal of low-pressure gas network，the detection distance is not less than 20m．