非平稳信号的分析方法是信号分析领域中的一个重要问题。本文以风洞试验获得的非平稳风压信号和升力系数信号为研究对象，采用HHT方法对信号进行时频分析。HHT（Hilbert-Huang transform）方法可以获得有意义的瞬时频率，从而给出频率随时间变化的精确表达；信号最终被表示为时频平面上的能量分布，成为Hilbert谱；该方法适用于分析生活中普遍存在的大量频率随时间变化的非线性、非平稳信号，可将复杂的信号直接分离成从高频到低频的若干阶固有模态函数。分析结果虽然没有表现出明显的频谱分布特性，但与以往HHT分析结果提取的固有模态函数不同，如果对本试验获得的非平稳信号提取的固有模态是低频部分的残余信号，忽略其他高频信号，则风压时程和升力系数时程的残余信号曲线就可以分别回归为一个线性函数和一个正弦函数。这也说明，该非平稳信号的主成分仍然是由平稳信号组成的，可以用分析平稳信号的方法进行时程分析。

The method of non-stationary signal analysis is a major issue in the field of signal analysis. Taking the signal of non-stationary wind pressure and lift coefficient obtained from wind tunnel experiment as research objects, time frequency analysis of the signal was presented by the method of HHT. Based on the method of HHT, the meaningful instantaneous frequency was obtained, as well as exact expression of frequency which changes with time; signal was finally expressed as the energy distribution in the time frequency plane as Hilbert spectral; this method can be applied to analyzing a large amount of nonlinear and non-stationary signals whose frequency change with time, and complex signal can be decomposed into a number of intrinsic mode functions from high- to low-frequency. However, analysis results do not show significant characteristics of special distribution, it is different from previous intrinsic mode function extracted by HHT; if intrinsic mode extracted from non-stationary signal obtained in this experiment is residual signal in the low-frequency part and high frequency signal is neglected, the curve of residual signal of time history of wind pressure and lift coefficient can regress a linear function and a sine function separately. It also shows that the components of this non-stationary signal are mostly stationary signal, and the time history of non-stationary signal can be analyzed by the method of stationary signal analysis.