In order to investigate the effect of steel fibers and polypropylene fibers on flexural behavior of HPC deep beams,four-point bending tests were conducted on 17 simply supported HPC deep beams with different fiber contents and steel bars.Results show that the first crack load of FRHPC beams (either single type or hybrid) is increased by 10%-40%,the yield load of hybrid FRHPC beams is increased by 50%-150%,and its ultimate flexural capacity is increased by 1-2 times.Thus hybrid fibers can be used to greatly increase the flexural capacity of HPC deep beams,but the failure pattern of hybrid FRHPC beams without steel bar is brittle failure,it means that hybrid fibers can not replace steel bars.The method to calculate the ultimate flexural capacity of hybrid FRHPC deep beams is discussed as well.