Abstract: Time-domain numerical simulation was performed by a high order computational aeroacoustics (CAA) approach in order to research the suppression of a micro-perforated panel absorber on combustion instability. Firstly, three dimensional acoustic perturbation equations with pressure time lag model were solved and frequencies of the engine were predicted. Then the acoustic impedance characteristic of a micro-perforated panel absorber was analyzed by an analytical method. A time-domain numerical simulation was carried out by multi-freedom broadband impedance model in order to research the impedance characteristic. The frequency predicted by numerical simulation showed good consistency with the experimental result. It is demonstrated that the computational aeroacoustics approach can recognize dangerous modes and analyze the suppression of a micro-perforated panel absorber on combustion instability, which can provide some reference for the engineering design of liquid rocket engine.