Ytterbium monosilicate (Yb2SiO5) is a promising candidate for environmental barrier coating. However, its mechanical and thermal properties are not well understood. In this work, the structural, mechanical, and thermal properties of Yb2SiO5 are studied by combining density functional theory and chemical bond theory calculations. Based on the calculated equilibrium crystal structure, heterogeneous bonding nature and distortion of the structure are revealed. Meanwhile, the full set of elastic constants, polycrystalline mechanical properties, and elastic anisotropy of Yb2SiO5 are presented. In addition, the minimum thermal conductivity of Yb2SiO5 was determined to be 0.74 W m−1 K−1. The theoretical results highlight the potential application of Yb2SiO5 in a thermal and environmental barrier coating.