The utility model relates to a two-stage planetary gear transmission device which comprises a sun wheel, an input shaft, a first planetary gear, a second planetary gear, a check ring, a planetary wheel axle, a bearing, a fixed inner gear, a shaft sleeve, a movable inner gear, a planetary carrier and an output shaft, the sun wheel is fixedly connected to the input shaft, the first planetary gear is arranged on the planetary wheel axle, the first planetary gear, the sun wheel and the fixed inner gear are meshed, the second planetary gear and the movable inner gear are meshed, the first planetary gear and the second planetary gear are arranged on the planetary wheel axle, the shaft sleeve is sheathed on the planetary wheel axle which is arranged on the planetary carrier by the bearing and the check ring, and the planetary carrier is fixedly connected to the output shaft. The product has a simple and compact structure, planetary gears in the two-stage planetary gear transmission device are duplicate gears, the input shaft transmits the rotation in the same direction to two members, namely the output shaft and the inner gear, so the two-stage planetary gear transmission device is small in size, light in weight, low in fault rate, convenient to maintain and low in cost, and can realize transmission in large transmission ratio.