Buzz phenomena of a typical supersonic inlet were studied with numerical simulations. The dynamic mode decomposition (DMD) method was introduced to analyze the flow characteristics of the little buzz and big buzz. The first order dynamic mode reflected the time-averaged flow field characteristics

and the second order dynamic mode showed the flow field features of the main frequency oscillation. In addition

the research on the relationship between little buzz and big buzz reveals that the flow of little buzz contains the oscillation characteristics of the big buzz

and little buzz regime is a transitional state from the steady flow field to the big buzz regime. During the evolution from the little buzz to the big buzz

some flow structures in the inlet are gradually weakened and tend to be stable

hence the overall flow field of the big buzz is more stable than that of the little buzz.