Recently, the shortage of fossil resources contributes to strict regulations of environmental protection. The research on the high efficiency and low emission of engines becomes an important direction all over the world. Technologies like high injection pressure, high supercharger and high back pressure have come into application. Increasing the injection pressure and average cylinder pressure results in the injected fuel converting into supercritical fluid, the spray atomization under supercritical condition is different from conventional spray process. This paper provides a numeral analysis of the injection and atomization process under supercritical condition in a constant volume vessel with high temperature and high pressure environment. In this paper, we establish a surrogate fuel composed of n-Haxadecath, HMN and 1-Metylnaphthalene, to analyze the supercritical injection and atomization process of diesel surrogate fuel with large eddy simulation (LES). The injection pressure is 180MPa, and the temperature in constant volume vessel is within the range of 600-800 K, and pressure is from 5 to 8 MPa. The simulation mainly focuses on the influence of high temperature and pressure in constant volume vessel on the injection and atomization process. As the result of simulation shows, when the surrogate fuel is injected into the nitrogen environment in supercritical conditions, the injection and atomization process is significantly different from the spray formation in the conventional engine because of the liquid structure affected by surface tension which is vanished in supercritical conditions. Moreover, as the temperature in constant volume vessel increases, the spray penetration increases and spray cone angle becomes wider. As the pressure in constant volume vessel increases, the spray penetration shortens and spray cone angle becomes narrower.