The invention relates to a technique of iodine cycles for hydrogen manufacturing, and aims to provide a method for promoting a Bunsen reaction in a thermochemical iodine-sulfur cycle for hydrogen manufacturing. The method comprises the following steps: adding I2 and H2O in a reactor, and heating a reaction solution to 30-72 DEG C; adding hydroiodic acid under the condition that the mass ratio of HI / H2O is 1 / 36-1 / 18: 1, and mixing the reaction solution at a uniform speed so as to ensure I2 is completely dissolved; feeding SO2 at a constant flow rate, and spontaneously carrying out the Bunsen reaction so as to obtain H2SO4 and HI; and in the presence of excessive iodine, carrying out the separation of liquid-liquid phases, so that the reaction achieves a liquid-liquid equilibrium state finally. According to the invention, the original gas-liquid-solid three-phase reaction is transferred into a gas-liquid reaction, and then the kinetic velocity of the Bunsen reaction is improved; and added HI has certain contribution to the improvement of the concentration of HI in a HIx phase in a thermodynamic equilibrium state, and HI achieves a super azeotropic concentration, so that the situation that pure HI steam is obtained through subsequent distillation is facilitated, and a HI concentration step can be cancelled, therefore, the method is extremely advantageous to the simplification of a whole SI circulation system and the improvement of the thermal efficiency of the system.