Abstract: In order to establish the method for calculating the crack width of high strength steel reinforced ultra-high-performance concrete (HSSRUHPC) flexural components, bending tests were carried out on six HSSRUHPC beams. The crack development process and the distribution characteristics of specimens were analyzed, and the applicability of a crack width formula in the existing design code for predicting the maximum crack width of an HSSRUHPC beam were evaluated. The study result showed that the vertical crack appeared at the pure bending section first for an HSSRUHPC beam by bending. After the tensile reinforcements yielded, the number of vertical cracks remained basically unchanged. Compared with SRC beams, the vertical cracks of an HSSRUHPC beam were narrow and densely distributed. For the crack width of an HSSRUHPC beam, the calculated results referring to the code of JGJ 138−2016 and YB9082−2006 were larger than test results. Therefore, the mechanical analysis method for the crack section of an HSSRUHPC flexural component during a normal use stage, and the stress level of UHPC, reinforcements and steel could be determined. And then the formulas were modified for calculating the stress of reinforcements, for the average crack spacing and, for the uniformity coefficient of steel strain. Finally, the formula for calculating the maximum crack width of an HSSRUHPC flexural component was established. The calculated results of the stress for tensile reinforcements and the tensile flange of the section steel, of the average crack spacing and, of the maximum crack width were verified by using the test results, and the two were in a good agreement.