As a new type of aerospace structure, flexible inflatable space structure has attracted more and more attention in the aerospace field such as air lock cabin and space residence cabin. Intelligent damage identification for such structures is of great significance for deep space and interstellar detection. Therefore, a real-time damage monitoring technology for space inflatable structures based on distributed optical fiber sensors is proposed in the paper. With the help of ANSYS finite element analysis method, the strain response and distribution law of the structure with cracks under internal pressure are obtained by numerical simulation. On the basis, a distributed fiber Bragg grating sensing system is arranged on the surface of the flexible inflatable structure braided by aramid fibers to collect real-time information of the surface strain distribution and change of the inflatable structure corresponding to different locations and degrees of damage. The identification parameters which characterize the crack characteristics of structures are extracted, and the corresponding relationship model between the strain response difference of sensors and the crack damage length is established to locate the crack damage area and identify the damage length. Results show that the proposed method has the advantages of non-visual measurement, good real-time performance and multi-function reuse, and can provide technical support for service state identification and on-orbit maintenance of space flexible inflatable structures in the future.