A dual-clutch automatic transmission, comprising: a first input shaft having a first end and a second end opposite to the first end of the first input shaft; a first clutch connected to the first input shaft at the first end of the first input shaft; a second input shaft having a first end and a second end opposite to the first end of the second input shaft; wherein the second input shaft is a hollow shaft and is sleeved on the first input shaft; a second clutch connected to the second input shaft at the first end of the second input shaft; a seventh-gear driving gearwheel, a first-gear driving gearwheel, a fifth-gear driving gearwheel and a third-gear driving gearwheel, which are individually arranged and are fixedly connected to the first input shaft; a fourth-gear driving gearwheel and a second-gear driving gearwheel, which are individually arranged and are fixedly connected to the second input shaft; wherein, the fourth-gear driving gearwheel is also used as a sixth-gear driving gearwheel, and the second-gear driving gearwheel is also used as a reverse-gear driving gearwheel in order to omit a reverse-gear shaft; a first output shaft and a second output shaft on which driven gearwheels respectively engaged with the corresponding driving gearwheels are rotatably supported; and a parking ratchet wheel; characterized in that the seventh-gear driving gearwheel, the first-gear driving gearwheel, the fifth-gear driving gearwheel and the third-gear driving gearwheel are sequentially arranged on the first input shaft along a direction from the second end of the first input shaft to the first end of the first input shaft; wherein the fourth-gear driving gearwheel and the second-gear driving gearwheel are sequentially arranged on the second input shaft along a direction from the second end of the second input shaft to the first end of the second input shaft; wherein a seventh-gear driven gearwheel, a fifth-gear driven gearwheel, a sixth-gear driven gearwheel and a second-gear driven gearwheel respectively and correspondingly engaged with the seventh-gear driving gearwheel, the fifth-gear driving gearwheel, the fourth-gear driving gearwheel and the second-gear driving gearwheel are rotatably supported on the second output shaft; and a first-gear driven gearwheel, a third-gear driven gearwheel and a fourth-gear driven gearwheel respectively and correspondingly engaged with the first-gear driving gearwheel, the third-gear driving gearwheel and the fourth-gear driving gearwheel, and a reverse-gear driven gearwheel are rotatably supported on the first output shaft; wherein the parking ratchet wheel is fixedly connected to the second output shaft between the fifth-gear driven gearwheel and the sixth-gear driven gearwheel. a first input shaft having a first end and a second end opposite to the first end of the first input shaft; a first clutch connected to the first input shaft at the first end of the first input shaft; a second input shaft having a first end and a second end opposite to the first end of the second input shaft; wherein the second input shaft is a hollow shaft and is sleeved on the first input shaft; a second clutch connected to the second input shaft at the first end of the second input shaft; a seventh-gear driving gearwheel, a first-gear driving gearwheel, a fifth-gear driving gearwheel and a third-gear driving gearwheel, which are individually arranged and are fixedly connected to the first input shaft; a fourth-gear driving gearwheel and a second-gear driving gearwheel, which are individually arranged and are fixedly connected to the second input shaft; wherein, the fourth-gear driving gearwheel is also used as a sixth-gear driving gearwheel, and the second-gear driving gearwheel is also used as a reverse-gear driving gearwheel in order to omit a reverse-gear shaft; a first output shaft and a second output shaft on which driven gearwheels respectively engaged with the corresponding driving gearwheels are rotatably supported; and a parking ratchet wheel; characterized in that the seventh-gear driving gearwheel, the first-gear driving gearwheel, the fifth-gear driving gearwheel and the third-gear driving gearwheel are sequentially arranged on the first input shaft along a direction from the second end of the first input shaft to the first end of the first input shaft; wherein the fourth-gear driving gearwheel and the second-gear driving gearwheel are sequentially arranged on the second input shaft along a direction from the second end of the second input shaft to the first end of the second input shaft; wherein a seventh-gear driven gearwheel, a fifth-gear driven gearwheel, a sixth-gear driven gearwheel and a second-gear driven gearwheel respectively and correspondingly engaged with the seventh-gear driving gearwheel, the fifth-gear driving gearwheel, the fourth-gear driving gearwheel and the second-gear driving gearwheel are rotatably supported on the second output shaft; and a first-gear driven gearwheel, a third-gear driven gearwheel and a fourth-gear driven gearwheel respectively and correspondingly engaged with the first-gear driving gearwheel, the third-gear driving gearwheel and the fourth-gear driving gearwheel, and a reverse-gear driven gearwheel are rotatably supported on the first output shaft; wherein the parking ratchet wheel is fixedly connected to the second output shaft between the fifth-gear driven gearwheel and the sixth-gear driven gearwheel.