In this article the structural, mechanical and thermal properties are investigated under pressures and temperatures by the first-principles calculations. The obtained results indicate that the value of V/V0 under different pressures slowly increases with the increase of temperature. The elastic modulus including bulk modulus, Shear modulus and Young's modulus of Li3BN2 increases with the increase of pressure. And pressure can improve the ductility and plasticity of Li3BN2. The vibrational free energy and enthalpy also increase with the increase of pressure, while the entropy and heat capacity gradually decrease with the increase of pressure.