Nowadays, the use of membrane structures has become widespread due to their remarkable properties such as lightness, high speed construction, architectural and aesthetic visual appearance, fire spreading prevention. However, there have been very few studies conducted on structural behavior and numerical simulation of these structures. In the present study, numerical simulation, natural frequency and mode shapes of hypar and double hypar membrane structures are discussed then, by changing the dimensions of the numerical model, the effect of dimensions on the structural performance of these types of structures is investigated. For this purpose, an experimental specimen was selected from literature and simulated by ABAQUS software. Experimental and numerical results showed a good convergence, which ensure the validity of the numerical simulation method. In the following, structural behavior of hypar and twin hypar was evaluated base on the obtained natural frequency; the difference between the height of the two-corners of the membrane was changed in the models and the effect of height difference on the natural frequencies was investigated. The results showed that increase of height difference in both single and twin hypar structures leads to increase of natural frequency and fabric consumption.