Abstract: Reinforced concrete (RC) beams incorporating Reactive Powder Concrete (RPC) in conjunction with high-strength steel bars (HSSB) offer the potential to fully utilize the strengths of both materials, resulting in the material consumption reduction and the structural durability improvement. To investigate the durability of RPC beams with HSSB, 20 RC beam specimens were designed to examine the deterioration mechanisms of the flexural performance of RPC beams with HSSB under the combination of chloride ion penetration and load. The experimental variables included steel reinforcement strengths (HRB400 and HTRB600), concrete types (C60 and RPC), and corrosion duration (0 d, 30 d, 60 d, 90 d, 120 d). The research result demonstrates that: under cracking loading and identical corrosion conditions, the corrosion rate of steel reinforcement and the degradation rate of load-carrying capacity in RPC beams with HSSB are slightly lower than those in RPC beams with conventional steel reinforcement. Moreover, compared to beams employing ordinary concrete, RPC beams present significantly lower steel reinforcement corrosion rates and degradation rates of load-carrying. Therefore, both HSSB and RPC materials can enhance the corrosion resistance of RC beams in the cracked state, while RPC materials exhibit a significantly greater improvement in corrosion resistance compared to HSSB.