In recent years, the 14th Five‐year Plan has put forward the urban renewal policy, followed by the demolition and reconstruction of old buildings in various cities in China. However, in the process of development, the treatment of the buildings with "large demolition and large construction" is the mainstream, thus ignoring the protection and inheritance of the old buildings, and the new buildings are too modular and not distinctive, resulting in the situation of "one thousand cities with one side" in many cities. This paper cites the "urban catalyst theory" as trying to study the new strategy and specific design techniques of old buildings renewal under the guidance of the catalyst theory, so as to promote the development of cities in society, economy, culture and other aspects, and coordinate the harmonious relationship between old buildings and people.