TC4 alloy is one of the most widely used aviation materials. Laser surface remelting (LSR) technology can effectively improve the mechanical properties of TC4 alloy, but the strengthening mechanism of LSR on the mechanical properties of TC4 alloy with bimodal microstructure is still unclear. In this paper, LSR treatment was performed on the front and back of TC4 samples, and then mechanical properties and tribological properties were tested. Systematic characterization was performed by TEM, EBSD, SEM and other instruments. The synergistic strengthening mechanism between layered heterogeneous structureSand bimodal microstructure was discussed. The results show that the remelted layer is composed of coarse martensite laths (CMLs), fine martensite laths (FMLs) with scattered orientations, and partially parallel compression twins. When the remelted layer underwent plastic deformation, dislocations activated, tangled and piled-up in CML. FML and twins wrapped around CML hindered the transfer of dislocation slip at the interface, resulting in a significant increase in the yield strength of TC4 alloy with bimodal microstructure to 879 ± 9 MPa, increase in the tensile strength to 1050 ± 5 MPa, and reduction in number of the fatigue cracks during wear testing.