Abstract: A total of 10 pieces of RC beams were fabricated and tested for the flexural reinforcement effect of basalt fiber reinforced polymer (BFRP) grid-engineered cementitious composites (ECC) on reinforced concrete (RC) beams and the influence mechanism of reinforcement parameters on reinforcement effect. The influence of the thickness of ECC, the number of BFRP grid layers, the size of BFRP grid, and the amount of BFRP grid reinforcement on the bending properties of RC beams were studied. An analytical model for predicting the ultimate bearing capacity of RC beams strengthened using this approach was also proposed. The experimental results show that the application of BFRP grid-reinforced ECC for strengthening RC beams can significantly enhance their flexural performance. Compared to the unstrengthened beam, the cracking load, yield load, and ultimate load of strengthened beams increase by 62.5%, 11.1% and 21.2%, respectively. Additionally, the strengthened beams exhibit improved ductility. Increasing ECC thickness effectively mitigates interfacial debonding failure, and beams reinforced with fewer grid layers and smaller sizes exhibit better strengthening effects. Furthermore, non-uniform thickness multi-layer arrangements of FRP grids, as opposed to uniform thickness multi-layer arrangements, leads to premature interfacial debonding due to inconsistent deformation among the reinforcement layers. Finally, the analytical model can provide a reliable estimation of the ultimate load-bearing capacity of the strengthened beams. The research findings offer theoretical support for the flexural reinforcement design of RC beams.