Abstract: In order to expand the calculation and analysis method research of acoustic ?eld generated by vortex pairing, the subsonic planar mixing layer vortex pairing is studied with numerical method. Direct numerical simulation (DNS) is employed to extract the acoustic source, the two dimensional frequency domain and time domain Kirchhoff methods are applied to extrapolate the far-field radiated sound, and the frequency domain method is employed to investigate the sound radiation from the twice vortex pairings. The frequency domain and time domain Kirchhoff methods are different in some degree, but the computation results compared with the DNS show that they reach the similar high order of accuracy. According to the analysis with frequency domain Kirchhoff method, it reveal clearly that each acoustic mode of the twice vortex pairings correspond to the vortex rolls and pairings respectively. Using the fre-quency domain method’s good performance of computational and analytica, this paper farther studies the influence of inflow instability waves with different phases on the acoustic field of vortex pairings, and exhibits that the dominant mode plays an important role in the acoustic field.