Abstract: The uniaxial constitutive relation of ultra-high performance fiber reinforced concrete (UHPFRC) is the basis for under-standing its material properties and nonlinear structural design. From the perspective of the constitutive equation function model, this paper reviews the existing research on the uniaxial constitutive relationship of UHPFRC. It was found that the empirical model of constitutive relation is suitable for structural design calculation, and the constitutive equations of uniaxial tension and compression should adopt rational fractions. The simplified model of constitutive relation is suitable for simplified force analysis and numerical simulation. The three-fold line model is suitable for uniaxial tension, and the double-fold line model is suitable for uniaxial compression. The damage model of constitutive relation is suitable for the study of material properties, and the damage evolution function is mostly Weibull distribution. In addition, it is found that the constitutive equations obtained by various existing studies do not contain fiber parameters, which cannot fully reflect the influence of steel fibers. Therefore, uniaxial tension and compression tests were carried out on UHPFRC with three aspect ratios and six volume fractions to analyze the influence of fibers on the constitutive relationship. The results show that the rational fraction is more suitable for the empirical model function of the uniaxial tension and compression constitutive model of UHPFRC. Combined with the test and the collected literature data, the influence of fiber on the coefficient of the empirical model equation was analyzed, and the equation of the empirical model of the uniaxial constitutive relationship was proposed. The influence of steel fiber parameters on the uniaxial damage constitutive relation was also explored. The experimental results show that there is a strong correlation between the steel fiber enhancement factor and the control coefficient of the damage model. Based on the experimental data, the relationship between the parameters of steel fiber and the control coefficient of constitutive equation is obtained by numerical analysis, and then the damage constitutive equations of uniaxial tension and compression including steel fiber variables are proposed. The literature data are collected for verification and correction, indicating that the constitutive relation proposed in this paper is in better agreement with the experimental results.