The bond behavior is the basis of collaboration between GFRP/steel wire composite rebar and concrete, and the bond-slip constitutive model is the overall reflection of bond behavior of GFRP/steel wire composite rebar embedded in concrete. Thus, the research on the constitutive model of bond-slip relationship between GFRP/steel wire composite rebar and concrete has theoretical and practical value in the performance analysis, design theory and engineering application of concrete structures reinforced with GFRP/steel wire composite rebars. In this study, 180 pull-out specimens were tested to investigate the effect of rebar rib spacing, rebar diameter, embedded length, concrete compressive strength, concrete cover thickness, and concrete cast depth on bond behavior, and the bond-slip curves were obtained for each specimen. Based on the existing bond-slip constitutive models worldwidely, one new bond-slip constitutive model was proposed according to the analysis of bond failure, bond-slip mechanism, and loading process of GFRP/steel wire composite rebar. The newly built bond-slip constitutive model was compared with the test results and existing bond-slip models. It is explicit in physical concept and simple in form, and fits the whole loading process of GFRP ribbed rebar and the test results well.