Abstract: In order to carry out the further analysis of an inflatable membrane structure during the phase of normal operation, a finite element modelling method for inflatable membrane structures is presented based on photogrammetry. The proposed method is divided into four steps. Firstly, the three-dimensional coordinates of the target points pasted on the external surface of an inflatable membrane structure are observed to build the membrane shape based on photogrammetry, and the internal pressure is measured by means of the pressure sensor. Secondly, after simulating the continuous membrane surface by the membrane links and by distributing the internal pressure to the according joint based on the measurement results, the force density of membrane link is calculated based on the force finding theory of a cable structure system with the linear adjustment theory. Thirdly, according to the equilibrium matrix theory and the small deformation assumption, the zero-stress state of inflatable membrane structures is solved by using the nonlinear generalized inverse matrix method. Fourthly, the finite element model of inflatable membrane structures during the process of normal operation can be built by introducing the internal pressure via ABAQUS based on the zero stress state. Finally, the proposed method is verified by the results of both measurement and calculation obtained from the model experiment of a triangular ETFE cushion.