一、问题缘起郊天礼作为中国古代皇帝祭天的重要礼仪,在汉魏以后国家祭祀中居于主导地位。商周时期是否已确立南北郊祀制度,不易确知,《春秋》书郊者凡九,学者以为“郊为夏正正月祈谷之礼”。在秦汉国家祭祀整合过程中,西汉末年王莽所定“元始仪”开启了汉魏以后国家郊祀制度之先河。在汉唐之间,以是否建立圜丘,郊天制度存在两种情况。The excavation to the yuanqiu （Circular Mound Altar） of the Sui and Tang Dynasties at the Tang Chang＇ an City roughly made clear the forms of the altar body and the neiwei （inner enclosure wall）. The contents about the .yuanqiu of the Sui and Tang Dynasties in the historic literatures of the Tang and Song Dynasties are helpful for us to clarify the forms of the sanwei （three enclosure walls of the yuanqiu） and the location of the liao-burning sacrifice altar. In the early Northern Song Dynasty, the forms of the yuanqiu and sanwei followed that of the Tang Dynasty; by referring to the relevant historic literature of the Song Dynasty, the sizes of the yuanqiu and sanwei of the Sui and Tang Dynasties could be understood and the exact location of the liao-burning sacrifice altar in Da Tang Kaiyuan Li （Ritual of the Kaiyuan Era of the Great Tang） could be accurately confirmed. The yuanqiu of the Sui and Tang Dynasties has been amended for many times, but the general forms of the altar and enclosure walls were almost unchanged. The location of the liao-buming sacrifice altar in the Zhenguan Xin Li （New Ritual of Zhenguan Era） and Da Tang Kaiyuan Li has altered, but was not moved beyond the basic rule for the location of liao-burning sacrifice altars in the southern suburb of the capital of the Han to the Tang Dynasties.