The purpose of this paper is to study the practice of elastic design concepts in the transformation of hybrid spaces in old factory buildings. Through an overview of the theory of elastic design and its application in urban architecture, the principles of elastic hybrid space design in urban architecture are proposed, including the principles of flexibility, openness, ambiguity and growth. Then the application mode of hybrid space transformation in old factory buildings is explored through research methods such as field research and literature case analysis. It is found that the concept of flexible design can provide an effective solution for the transformation of old factory buildings, realizing the flexibility, openness and sustainability of the space. The conclusion shows that the application of elastic design concept in the transformation of old factory buildings can effectively solve the problems of reuse of old factory buildings and urban renewal, which is of great significance to the sustainable development of cities. This study provides a new idea and method for the hybrid space transformation of old factory buildings, which is of practical significance.