To　investigate　the　issues　of　transverse　through　cracks　and　interlayer　damage　of　the　CRTS　III　slab　ballastless　track　under　train　loading,　the　digital　image　correlation　(DIC)　technique　was　employed　to　reveal　the　damage　mechanisms　of　the　reduced-scale　concrete　of　track　slab　structural　concrete　(TSSC)　and　track　slab-filled　laminated　structural　concrete　(TSLSC).　The　results　indicate　that　under　train　loading,　the　transverse　through　cracks　of　TSLSC　exhibit　a　multi-stage,　layer-by-layer　cracking　characteristic,　and　there　is　a　risk　of　cracking　in　ballastless　track　when　the　bottom　longitudinal　strain　exceeds　0.0004.　The　sudden　increase　in　interlayer　longitudinal　shear　strain　difference　in　the　third　stage　under　train　loading　demonstrates　that　shear　stress　is　the　primary　cause　of　interlayer　damage　in　ballastless　track.　Tensile　damage　models　based　on　ultimate　stress-strain　relationship　and　yield-fracture　strain　were　established,　and　a　non-contact　testing　method　for　the　constitutive　relationship　and　energy　absorption　effect　of　ballastless　track　was　proposed　using　DIC　technology,　aiming　to　provide　reference　for　the　analysis　and　prediction　of　ballastless　track　damage　under　train　loading.