In this study, the crush behavior and energy absorption of various thin-walled structures under quasi-static loading are investigated. Some experimental data from similar work was used for validation of a simulated model. Some samples were designed and considered with different combined geometries. It was found from simulated model that the most ability of specific energy absorption and crush force efficiency are related to the circle-square sample. For the circle-square sample, the analytic equations for calculating the mean crush force are obtained. The mean crush force result was compared with the result of simulations, showing a good agreement. The multi-objective optimization process for the circle-square structure was performed using non-dominated sorting genetic algorithms for two statuses. The purpose of optimization is to increase the specific energy absorption and to decrease the peak crushing force which causes the increase of crush force efficiency amount. The amount of specific energy absorption in the second status compared to the first status was improved by 17% and the amount of crush force efficiency was improved by 12% after optimization process.