In order to study the influence of stoichiometric ratio and oxygen content of oxidant on detonation process of gelled gasoline/gas-phase oxidant， a three-dimensional two-phase detonation model of gelled gasoline and gas-phase oxidant was established， and the internal detonation process of pulse detonation engine was simulated numerically using conservation element and solving element method. The effect of stoichiometric ratio and oxygen content of oxidant on the formation time， formation distance， peak pressure and propagation velocity of detonation wave were analyzed. The numerical results indicated that when the stoichiometric ratio is lower than 1.15， the formation distance and time of detonation wave decrease with increasing of stoichiometric ratio， and the pressure peak and propagation velocity of detonation wave increase at the same time. When the stoichiometric ratio is of 1.15， the formation distance and time of detonation wave are 0.288 m and 278 μs， and the pressure peak and propagation velocity of detonation wave are 1.85 MPa and 1437 m·s^-1， respectively. The pressure peak and propagation velocity of detonation wave increase with increasing oxygen content of oxidant， and when the oxygen content increases from 23% to 48%， the pressure peak and propagation velocity of detonation wave increase from 1.85MPa， 1437 m·s^-1 to 2.85MPa， 1868 m·s^-1， respectively.