Urban Green Infrastructure (UGI) is a main builder of urban natural landscape and ecological environment by providing the key ecosystem services for residents. Discussing the spatial relationship between supply and demand of UGI ecosystem services is of great scientific significance for urban ecological construction and green space planning. Based on population, GDP, and land use data, this paper explored the spatial pattern between supply and demand of UGI ecosystem services in built-up area of Xi'an, and the spatial relationship between supply and demand of UGI ecosystem services in four urban functional areas were also analyzed. The results showed that the total UGI ecosystem service supply in Xi'an built-up area was 423 million yuan. The supply of ecosystem service gradually decreased from the edge of the study area to the central area, while the demand of ecosystem service showed the opposite change. The supply and demand of UGI ecosystem services in Xi'an had a significant negative spatial correlation, and there were significant differences among different functional areas of the city. The supply of UGI ecosystem services in built-up areas did not match the spatial distribution of urban demand of ecosystem services. It is urgent to coordinate the supply and demand of ecosystem services through rational UGI construction.