Aiming at the disadvantages of mathematical models for foamy-oil flow at present，the concepts of pseudo-bubble-point pressure and relaxation time in pseudo-bubble-point model and supersaturation model were introduced，and three depletion experiments of long cores were conducted. On this basis，a new mathematical model for foamy-oil flow was established. In this model，foamy oil is viewed as pseudo-single-phase flow，and the effective permeability of porous media varies with pressure depletion rate，oil viscosity and gas saturation，and thus an mathematical expression of effective permeability was put forward by analysis of the experimental data. The viscosity of foamy oil is approximately equal to that of saturated oil under the same conditions. The compression factor of foamy oil is treated as a linear combination of the compression factors of oil and gas phase. During foamy oil flows，the supersaturation in the depletion process has been considered as well. In order to verify the correctness of the model，results from the proposed model，the pseudo-bubble-point model，the supersaturation model and the black oil model were compared with the experimental data respectively. It shows that the new model fits the experimental data well，however，the other three models’calculations deviation is large.