Abstract: Pure silicide coating and Zr modified silicide coating were prepared on surface of TC4 alloy by diffusion penetration with the penetration agent composed of 15Si-5NaF-80Al₂O₃ and 15Si-10Zr-5NaF-70Al₂O₃ (mass fraction/%), respectively. The microstructure and the solid particle erosion resistance at diffrerent errosion angles of the two coatings were studied and compared. The results show that the two coatings consisted of three layers, including an outer layer composed of (Ti,X)Si₂ (X=Al, V or Zr) phase, a middle layer composed of TiSi phase and an inner layer composed of Ti₅Si₄ and Ti₅Si₃ phases. The Zr modified silicide coating had a relatively dense structure, and no cracks existed. The erosion rate of the two coatings increased with the increase of the erosion angle, and the Zr modified silicide coating showed a better solid particle erosion resistance than the pure silicide coating. The Zr modification improved the solid particle erosion resistance of the silicide coating more significantly at a high erosion angle than at a low erosion angle.