Combustion instability often occurs inside the combustion chamber of aerospace engine. Almost every rocket engine using liquid fuel suffers combustion instability problem during R&D process. High frequency pressure oscillation inside the combustor, categorically those higher than 1kHz, can lead severe vibration to engine component and cause significant engine damage in a very short time. Dealing with this problem is one of the main subjects while developing rocket engine with superior stability and reliability. Fuel atomization and evaporation, one of the controlling processes of combustion rate, is an important mechanism of the combustion instability. To decrease and control the combustion instability, it challenges a deep understanding of the underlying mechanism of fuel atomization and evaporation process. In this paper, acoustic field was established to simulate the pressure fluctuation. Transient spray images of ethanol and aviation kerosene were recorded using high-speed camera. The obtained images were processed by MATLAB to extract and analyze the related data. Spatial fuel atomization characteristics was experimentally examined by multi-threshold image processing to analyze the effect of the high frequency acoustic field on the fuel break-up and disintegration, to gain deeper insight into the atomization characteristics of ethanol and aviation kerosene under different conditions. The results show that the half spray cone angle on the side with speaker is suppressed by the presence of the acoustic field compared with the case without speaker, and is smaller than the half spray cone angle on the side without speaker when the acoustic field is excited. Also, it turns out the frequency of the acoustic field influences the atomization characteristics of ethanol and aviation kerosene.