Abstract: The prophecy that “the tide passes through the Yiting and the number one scholar comes out” spread in Suzhou from Southern Song Dynasty to Ming and Qing Dynasties,which it had made the custom of watching the tide in August of the lunar calendar in Kunshan.The natural geographical background of the tide crossing the Yiting was due to the rising sea level which caused the tide boundary to move westward in Song Dynasty,and the Loujiang River became the main channel of Taihu Lake into the sea after Yuan Dynasty.The leaders of Kunshan scholars contributed to the building of the Asking-tide Hall and the making of the custom of watching the tides in August in Southern Song Dynasty,for they believed in the authenticity of the prophecy and they also wanted to motivate the scholars and educate the public.The local officials,famous families and scholars jointly maintained this custom for the prophecy came true,and it did not ceased until the end of Southern Song Dynasty.In order to improve geomantic omen,the Yuzhu Pagoda was built and the custom of watching the tide on August 18 was re-made in Ming and Qing Dynasties.The custom of watching the tide in Kunshan was not only subject to the change of natural geographical conditions,but also stemmed from the joint role of local officials and scholars.Through the making and re-making of buildings and customs,those materialized landscape shaped the locality and strengthened the local identity.In this process the local tradition had been creatively transformed and innovatively developed,and the local context had also been extended.