The invention relates to a two-stage planetary actuator. The two-stage planetary actuator comprises a motor assembly and a case. The case is fixedly connected with a shell of the motor assembly in a butt joint mode. A first-stage planetary assembly and a second-stage planetary assembly which are connected in series are arranged on the front portion of the case. The first-stage planetary assembly comprises a planetary box fixed in the case and further comprises a first-stage center shaft, wherein a bearing seat provided with a bearing is arranged in the middle of the planetary box; a planetary plate is fixedly connected to the rear end of the first-stage center shaft, and teeth are arranged at the front end of the first-stage center shaft; the middle of the first-stage center shaft is fixedly connected with the inner ring of the bearing; a plurality of planetary gears are installed on the planetary plate; the end of a motor shaft of the motor assembly is provided with teeth and is in engaged connection with the planetary gears. The second-stage planetary assembly comprises a planetary box which is fixed to the end of the shell and further comprises an output shaft, wherein a bearing seat provided with a bearing is arranged in the middle of the planetary box; a planetary plate is fixedly connected to the rear end of the output shaft, and teeth are arranged at the front end of the output shaft; the middle of the output shaft is fixedly connected with the inner ring of the bearing; a plurality of planetary gears are installed on the planetary plate; the end of the first-stage center shaft is in engaged connection with all the planetary gears.