Tungsten and tungsten-based materials are one of the most promising candidate of the first wall material faced plasma atmospheres for future nuclear fusion devices, and their brittleness and mechanical properties have always been the focus of attention. Herein, the tensile behavior at 300~800 °C of W-Y₂O₃ composites after recrystallization annealed at different temperatures and pure W after stress relief annealed were comparatively assessed at 300~800 °Cvia high temperature tensile testing machine, in terms of the effect of addition of rare earth oxide Y₂O₃ on the mechanical properties of W-composites. It was found that with the increasing temperature, the tensile strength of W and W-Y₂O₃ composites decreased gradually, and the corresponding break elongation increased first and then decreased; while the tensile behavior of W and W-Y₂O₃ composites all follow the ductile-brittle transition process, namely brittleness-pseudoplasticity-intrinsic plasticity. If tensile testing at the same temperature, W-Y₂O₃ composites exhibit better high plastic behavior than pure W. Whereas, W-Y₂O₃ composites present the best plasticity and toughness at 600 ^oC, with a break elongation even up to ~46%. In addition, from the acquired tensile curves, it is found that the temperature at which pure W exhibits plastic behavior is near 400 °C, while the temperature at which W-Y₂O₃ exhibits plastic behavior is near 300 °C. The constitutive equation of their strain hardening stage shows that pure W followed the power function strengthening behavior dominated by Hollomon's equation, while W-Y₂O₃ shows logarithmic function strengthening behavior in the early stage of uniform plastic deformation, and the same power function strengthening behavior as that of pure W in the later stage of uniform plastic deformation. It follows that the addition of Y₂O₃ can significantly enhance the plasticity and toughness of W composites, while reducing their brittleness and ductile-brittle transition temperature.