Abstract: When oilfield development is in medium-later period,gas will occur in fluid flow due to the draw down of reservoir pressure. But most of current well, test interpretution methods tuke no account of the effect of gas phase. Well test interpretution methods tuke no account of the effect of gas phase. A new well test interpretution model for oil-gns two-phase flow is estublished by use of H function,and the interpretution method is presented in this paper. The field application results indicate that the average formation pressure calculated by this method is more accurate than that by orginalmethod.