Abstract: It is necessary to analyze the dynamic deployment performance of space membrane structures for ensuring the surface accuracy and signal gain of spacecraft composed of thin membrane structure，such as inflatable deployable antennas，mesh deployable antennas，and solar sails.The whole thin membrane reflector was discretized into many constant strain triangular elements of which the nodes could be regarded as particles by using the finite element method.Under the premise of considering the elastic potential energy of the triangular element，the equilibrium equation of the triangular element was obtained by the principle of minimum potential energy，so as to realize the transformation between the strain of the point on the element and the strain of the three oblique edges of the element.Finally，the contact model was established to prevent the contact between elements in the deployment process from happening，and the mass matrix and stiffness matrix of the structure were assembled by the discrete topology of the thin membrane reflector，and the dynamic equation was established.Based on the results the dynamic model can simulate the deployment of the membrane accurately，and can be applied to analyzing the deployment performance of the membrane structure.

Key words: space membrane structure, the principle of minimum potential energy, the dynamic equation, deployment, triangular element