[en] Highlights: • Correlation of microstructure and mechanical properties of WK is discussed. • Correlation of its mechanical properties and thermal shock resistance is studied. • Thermal conductivity decreased, fracture toughness increased with higher K content. • WK with 82 ppm K presents the best tensile strength and thermal shock resistance. • This study can help to design materials with high thermal shock resistance. - Abstract: The microstructure of the materials always has a great impact on their mechanical and thermal properties, and hence on the thermal shock resistance. It is, therefore, of great concern to investigate the correlation between the microstructure, mechanical/thermal properties, and thermal shock resistance of K-doped tungsten (WK) alloys that have recently generated considerable research interest in nuclear fusion materials community. Thus, in this study, a series of highly dense K-doped tungsten alloys with close grain size values (within a narrow range around 3.5 μm) but different K bubble characteristics, i.e., average bubble sizes (33.7 nm → 82.1 nm), were fabricated through controlling the K content (46/82/108/122/144 ppm). The thermal conductivity decreased, and the fracture toughness increased, with the increased K content, while the WK samples with K of 82 ppm presented the highest tensile strength and thermal shock resistance. The correlation between the microstructure, mechanical/thermal properties, and thermal shock resistance of K-doped tungsten alloys are then discussed. These investigations can help to design highly thermal shock resistant materials with high strength and toughness.