Abstract: The research on facture parameters is one of the key projects on UHPFRC (ultra high performance fiber reinforcement concrete). The effects of steel fiber on stress intensity factor and crack tip opening displacement are assumed to be linear, and short steel fibers are assumed to distribute in UHPFRC randomly. Based on these assumptions, the fracture parameters, i.e. critical stress intensity factor and critical crack tip opening displacement, are expressed in terms of fiber geometrical parameters and physical parameters, and the computational coefficients of R-curve are derived accordingly. Next, load-deformation relationship of the three points bending UHPFRC beam are developed with different initial notches. At last, loading tests are carried out to verify the fiber reinforcement model.