To investigate the shear performance and load-transfer mechanism of stud-PBL composite shear connectors in steel-concrete composite structures, 12 groups of push-out tests were conducted on composite shear connectors with different configurations embedded in normal concrete (NC) and steel fiber-reinforced concrete (SFRC). A numerical model incorporating the bond-slip behavior at the steel-SFRC interface was developed to systematically analyze the failure characteristics, evolution of load-bearing capacity, and stress transfer mechanisms. The results indicated that the steel-NC specimens exhibited brittle failure characterized by concrete slab splitting and stud shearing, whereas the steel-SFRC specimens demonstrated delayed and sparse crack propagation due to the bridging and toughening effects of steel fibers, achieving an approximately 18.4% enhancement in shear capacity. The load-bearing capacity of specimens with studs welded to H-shaped steel was approximately 21.49%~27.59% higher than those with studs welded to perforated steel plates. The former primarily failed via stud shearing, while the latter experienced stud bending deformation owing to the strong constraint effect of penetrating reinforcement. The shear capacity of the composite shear connectors was jointly borne by the studs, penetrating reinforcement, concrete dowels, and the bond interaction between steel and concrete. The numerical model considering steel-concrete bond effects significantly improved simulation accuracy, particularly in the full-range load-slip simulation of steel-SFRC specimens, which exhibited excellent agreement with experimental results. The synergistic application of composite shear connectors with SFRC effectively balances high load-bearing capacity and ductility requirements, providing theoretical and experimental support for the optimized design of steel-SFRC composite structures.