Condensate gas pools can be classified into the primary condensate gas pool and the secondary condensate gas pool. The primary condensate gas pool is formed by generation of condensate by organic material and then migration into a pool as gas phase. During the formation of the primary condensate gas pool there is no phase change in the pool. But the secondary gas condensate pool was formed by solution of light oil in gas in the pool. During the formation of the secondary condensat pool there is phase change in the pool. The paper analyses the mechanism of the formation of the condensate pool and distribution of phase in the section. Finally the paper indicates that the distinction between the two types of condensate gas pool is important.