Chang 'an City in Tang Dynasty was established on the basis of the old system of Daxing City in Sui Dynasty, which was more magnificent than that in Sui Dynasty. The layout of Chang 'an City is very distinctive. Palace, yamen, square and city are separated, and Miyagi is located in the middle of the north of the city, which is the palace area. To the south is the imperial city, where the central government office is located; Outer Guo Cheng guards the Imperial City and Miyagi from the east, west and south, which is the residential and commercial area for ordinary people and bureaucrats. The two sides of the north-south central axis of the city are symmetrical, and there is no worry about a chessboard street, which is straight. Chang 'an City, with its large scale and neat layout, is a rare urban design in feudal times and has great influence at home and abroad.