By adjusting nozzle throat area, a sin gle-chamber dual-thrust solid rocket motor can produce more thrust ratio with a smaller pressure ratio to enhance overall performance of the solid rocket motor. In the paper, a nozzle throat area adjustment mechanism of a sin gle-chamber dual-thrust solid rocket motor was described. The pressure difference based on the gas pressure of the rocket motor itself can be obtained in the adjustment mechanism to drive the adjustment device, thereby completing the throat area control. The working principle of the adjustment mechanism was discussed in detail and its feasibility was verified through the work process simulation and simulation test., the nozzle investigated in this paper has advantages including simple structure and easy realization.