Abstract: Fluid composition, temperature, porous media, and non?equilibrium effect are the main factors affecting dew?point pressure. In process of gas injection development of gas condensate reservoir, the fluid composition in formation is of great difference in distribution due to sweep efficiency effect. Before cyclic gas injection or during depletion development, the fluid in formation appears gas phase behavior when the formation pressure is higher than the dew?point pressure, and such a fluid could be approximately regarded as a gas phase behavior. Under the cyclic gas injection, the change of the fluid composition in the formation is very complicated, and the fluid phase behavior will change with fluid composition, formation pressure and temperature. Based on the theory of equation of state, the typical fluid samples from a real gas condensate reservoir are selected in this paper, three changing trends of phase behavior in the process of cyclic dry gas injection are presented, and the PVT test results from the real samples are compared. Finally, the distribution characteristics of dew?point pressure is given, integrated with studies of simulation and calculation for the gas condensate reservoir