Space fragmentation is an important issue to be deepened in the study of urban spatial structure. The measurement index of urban space fragmentation is constructed from three dimensions of form, connection and function, and its pattern characteristics and influencing factors in Changsha are discussed by using geographical detector model. The main conclusions are as follows: (1) fragmentation of urban space can be measured from three aspects: morphological segmentation, contact barrier and functional disorder. Morphological segmentation can be characterized by mean block area index (MBA), contact barrier can be featured by average impedance index (AI), and functional disorder can be reflected by functional diversity index (FD) and adjacency conflict index (AC). (2) The spatial fragmentation of Changsha presents a pattern of circle-shaped differentiation and fan-shaped expansion differentiation. The low-fragmentation area is mainly distributed in the urban core area, while the high-fragmentation area extends to the periphery along specific sectors, and is mainly distributed in large-gated communities, industrial parks, mountain green areas and large railway stations. (3) The spatial differentiation of urban space fragmentation is the result of the joint action of multiple factors, among which the natural conditions such as altitude and slope are the basic factors, while land price, population density and facility input are the dominant factors. (4) The governance of urban space fragmentation in Changsha should break through the constraints of market supply, market demand and facility abundance. In order to reduce the negative effect of space fragmentation, the corresponding countermeasures should be adopted.