Abstract: It is a contrast experiment, the waveforms with different offset in both axial symmetric borehole and axial asymmetric borehole are recorded. The two-dimensional spectrum in wave-number and frequency domains is also calculated and compared with the result of numeric simulation with 2.5-D finite difference method, and a consistent result is obtained. Which demonstrate the accuracy of our study of acoustic field in an axial asymmetric borehole by using 2.5-D finite difference method.