Ecological space is an important guarantee of habitat environment in urban agglomeration area. Exploring the spatial expansion pattern and influencing factors of recreational utilization of ecological space (RUoES) in urban agglomeration is helpful to construct a balanced and shared ecological recreation service system, and improve the functions of urban agglomerations. Taking the Pearl River Delta urban agglomeration as the research object, this paper analyzed the spatial expansion characteristics of RUoES from 1990 to 2017 in terms of the spatial quantity and area, and explored their influencing factors. The results showed that:(1) in terms of the expansion of the number of RUoES, it has the spatial characteristics of "expanding from a few points inward and outward at the same time → partially filling from the marginal zone to the core area"; (2) The scale of utilization of ecological space for recreation presents the characteristics of "a few large-scale isolated spots → simultaneous expansion within the marginal area and built-up area → center filling"; (3) The spatial expansion of ESRU is mainly affected by population growth, urbanization, leisure and tourism demand, regional ecological space governance policy and urban agglomeration planning. The current study summarizes the law and causes of the expansion of RUoES in urban agglomerations, and suggests that urban agglomerations should promote the RUoES within the whole region through the optimization of ecological governance policies and overall planning, and pay attention to the coordination of the ecological recreation space allocation with the development of population and urbanization, and changes in leisure tourism demand.