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