This paper aims to investigate the crashworthiness performance of thin-walled tubes under quasi-static conditions both experimentally and numerically. Single-cell and multi-cell tubes made of aluminum were tested under quasi-static compressive loading. A three-dimensional finite element (FE) model accounting for the damage in the constitutive equations was developed. It was validated through experiments based on the force-displacement behavior and the deformation views of the tubes. The sensitivity of the initial peak force, total energy absorption, specific energy absorption, and crush force efficiency to different model parameters such as the tube height and thickness, velocity of the rigid upper plate, and the type of the constitutive equations used were investigated in detail. It was observed that the element type used (shell/solid) in the FE model and the element size in the thickness direction played an important role in simulating the tests accurately. In addition, surrogate-based optimization of the single-cell tubes (T0) and two different types of multi-cell tubes (T4E, T8E) is performed to maximize crush force efficiency (CFE) and specific energy absorption (SEA). It is found that CFE of the optimum T4E design is 8.5% greater than CFE of the optimum T8E design and 30% greater than CFE of the optimum T0 design. It is also found that SEA of the optimum T4E design is 9.8% greater than SEA of the optimum T8E design and 213% greater than SEA of the optimum T0 design.