An experimental study was conducted in the lean-premixed swirl-stabilized combustor at atmospheric pressure and temperature in order to analyze the pressure oscillation in occurrence of the combustion instability. The fluctuating pressure signals exhibited as non-stationary signals. A new method using Hilbert-Huang transform(HHT) based on empirical mode decomposition(EMD) and intrinsic mode function(IMF) reconstruction was investigated. This method was applied to demonstrate the characteristics of pressure oscillations in the lean-premixed combustor when the equivalent ratio was at 0.71 and 0.80. The pulsating signals were decomposed with EMD

and IMF containing specific frequencies was obtained. Through the HHT and statistical analysis

the instantaneous frequency of the IMF was analyzed. The results show that the pressure oscillations display the characteristics of intermittent pulsating

and present the beat at the equivalent ratio of 0.71; whereas at the equivalent of ratio 0.80

the pressure oscillations feature the limit cycle. The validity of this method proves that the IMF reflects the inherent mode when the combustion instability occurs

and it has a strong adaptability.