This paper explores the issue how to improve utilization ratio of CFRP strengthening steel structure in allusion to the diseconomy of steel structure strengthened with CFRP. An experiment including six single axisymmetric steel beams was carried out to study ultimate capacity of single axisymmetric steel beam strengthened with CFRP sheets. These samples were divided into three groups, and each group included two samples strengthened with one and two layers of CFRP sheets respectively. The experimental results show that single axisymmetric steel beam strengthened with CFRP is advantageous over biaxial symmetrical steel beam because the former has superior material utilization ratio. On the basis of the experimental results, a simplified analytical model is put forward for prediction of capacity and material utilization ratio. In the proposed approach, ultimate capacity formula is established and an index named material utilization ratio is suggested to study how to enhance CFRP utilization ratio. The analytical calculation results state clearly that steel beam strengthened with enough CFRP is favorable in improving capacity and material utilization and owns optimal utilization ratio. Above all, the proposed approach is convenient and accurate enough for practical application in material utilization assessmetn and capacity design.