To study the combustion characteristics of a rocket engine under continuous throttling, a continuous throttling experiment was conducted by using GOX(gaseous oxygen)/kerosene as propellants. Mass flow rate of kerosene was continuously throttled by a throttleable cavitation Venturi nozzle. Successful ignition under fuel rich condition (mixture ratio ranged from 0.405 to 0.690) and the continuous throttling of mixture ratio and combustion gas flow rate were achieved. Results show that chamber pressure increases with the decrease of kerosene flow when the mixture ratio is less than 0.535 but decreases when the mixture ratio is greater than 0.535. Meanwhile, characteristic velocity and combustion efficiency increase with the increasing mixture ratio, but the increasing ratio is bigger when the mixture ratio is less than 0.535 than that when the mixture ratio is greater than 0.535. The results indicate that the mass flow rate of propellants and combustion efficiency simultaneously affect the chamber pressure. Combustion efficiency dominates the chamber pressure when the mixture ratio is less than 0.535 while mass flow rate of propellants dominates when the mixture ratio is greater than 0.535.