Compared with other cross section shapes of thin-walled tubes, octagon multi-cell thin-walled tubes have the characteristics of compact structure and high specific energy absorption. The energy absorption characteristics of octagon multi-cell thin-walled tubes under quasi-static axial loading were simulated with finite element software Abaqus. The effects of the cross sections shape and structural parameters on energy absorption characteristics of the multi-cell tubes were analyzed. According to the indicator of the energy absorption characteristics, a side to side distribution of the octagon multi-cell tubes (S2S) was optimized by using the non-dominated sorting genetic algorithm. The results show that the energy absorption characteristics of the side to side distribution is better than the corner to corner distribution, and the octagon multi-cell S2S tubes is optimal; and structural parameters significantly influence its energy absorption characteristics; the octagon multi-cell S2S tubes optimized has better energy absorption characteristics, the specific energy absorption is increased by 33.11%, and the peak crushing force is reduced by 3.78%.