Abstract: To investigate the flexural performance of symmetrically inclined beams made of high-performance lightweight aggregate concrete with mixed fibers, four-point bending static load tests were conducted on five beams, with different fiber mixing methods and longitudinal reinforcement ratios as the primary parameters. By observing the development of cracks and failure modes of the beams, The impact of different fiber mixing methods on the beam's flexural performance was analyzed. The feasibility of using fibers to partially replace longitudinal reinforcement was explored. Considering the effects of fibers and axial force on symmetrically inclined beams, a formula for the ultimate bearing capacity of hybrid fiber-reinforced high-performance lightweight aggregate concrete symmetrically inclined beams was established. The study found that hybrid fibers can effectively improve the flexural performance of high-performance lightweight aggregate concrete beams, effectively suppress crack propagation, and enhance the ultimate bearing capacity of the beams. Hybrid fibers can partially replace longitudinal reinforcing bars. Mixing 40 kg/m³ steel fibers, 3 kg/m³ macro-polypropylene fibers, and 0.7 kg/m³ micro-polypropylene fibers, or mixing 50 kg/m³ steel fibers and 0.7 kg/m³ micro-polypropylene fibers, can replace longitudinal reinforcing bars with a reinforcement ratio of 0.328%. The mixture of 40 kg/m³ steel fibers, 3 kg/m³ macro-polypropylene, and 0.7 kg/m³ micro-polypropylene fibers has a better effect on improving the beam's bending stiffness, ultimate load capacity, and deformation ability. The ultimate load-bearing capacity calculation model has a high degree of consistency with experimental results.