Abstract: In order to investigate the flexural performance of ultra-high performance fiber reinforced cementitious composite material (UHPFRC) doped with copolymer formaldehyde fiber, five groups of bending specimens were designed and tested, including three groups of single mixed specimens and two groups of fiber hybrid specimens. The results show that among the copolymer formaldehyde fiber UHPFRC specimens, 2vol% copolymer formaldehyde fiber UHPFRC specimens have better flexural strength, with an average strength of 13.4 MPa. An appropriate amount of co-formaldehyde fiber can delay the cracking of UHPFRC matrix and enhance its ability to deformation before cracking. Among the five groups of test pieces, the cracking deflection of 2vol% copolymer formaldehyde fiber UHPFRC test piece is the largest, which can reach 0.65 mm. Hybrid fiber can better enhance the flexural strength and toughness of UHPFRC. When 1.5vol% copolymer formaldehyde fiber and 1.5vol% steel fiber are mixed, the flexural strength of UHPFRC specimens can reach 13.9 MPa, and the toughness of this group of specimens is the best. The research reveals the effect of copolymer formaldehyde fiber on the flexural mechanical properties of UHPFRC, which has important reference value for its application in UHPFRC and the promotion of UHPFRC.