Flash atomization has applied more and more to reduce drop sizes and to promote fuel vaporization in various engines. Thus, it is very important and necessary to scientifically and correctly understand the mechanism of flash atomization. The purpose of this research was to gain a better understanding of the flash atomization of aviation kerosene (RP-3). First, the bubble-point temperatures of aviation kerosene over a wide range of ambient pressures were investigated by using a common method. A simple and practical correlation for the bubble-point temperature was developed, taking the bubble-point temperature as the function of ambient pressure. The calculated values were in good agreement with the experimental ones. Furthermore, experiments were carried out to study flashing of superheated kerosene jets by ejecting superheated liquid aviation kerosene into a vacuum chamber through five different plain orifice spray nozzles. Superheated liquids were observed to spray in four different patterns: conventional pressure spray, boiling spray, flashing spray, and fully flashing spray. Fully flashing spray was defined as the form in which no distinguishable interface between the injected fluid and ambient gas existed. It is desirable to determine the methods governing the flash atomization process. Therefore, the effects of the operation parameters on critical superheat degrees for flashing and fully flashing were investigated. The results demonstrated that the initiated flash atomization reflects a combined effect of cavitation and superheating. However, cavitation was not necessary in the fully flashing process, only superheating was needed. The influences of the operation parameters on the spray width, spray cone angle, and core liquid length were also studied using a high-speed camera. The results again indicated that cavitation and superheating were the key factors in flash atomization.