The thermal sintering and infrared transparency of YSZ thermal barrier coatings (TBCs) greatly limit its thermal insulation and service lifetime. To address this, YSZ-LaMgAl11O19 (YSZ-LMA) composite TBCs consisting of YSZ/LMA splat interfaces aligned parallel to the coating surface are designed and prepared. The pinning effect of La3+ on YSZ splat boundary inhibits the healing of inter-splat pores, and the flake-like morphology of LMA allows coating to maintain micropores at high temperature, thereby enhancing its sintering resistance. The parallel YSZ/LMA interfaces with different refractive indexes form a multilayer structure aligned perpendicular to the coating surface which increase the multi-reflections of thermal radiation within the coating and improve the thermal radiation blocking. Consequently, YSZ-LMA TBCs show a higher thermal radiation reflectance and relatively lower thermal conductivity than YSZ TBCs after a heat treatment at 1300°C for 200 h, resulting in a reduction of simulated substrate temperature by up to 36.7 K.