Abstract Effect of the hot-pressing temperature (1750–1950 °C) on the microstructure and mechanical properties of the hot-pressed ZrB 2–SiC–ZrO 2f ceramics was investigated in detail. It was indicated that when the hot-pressing temperature was above 1900 °C, ZrO 2 fibers were instable in ZrB 2–SiC matrix which would degenerate into particles and the grain size of ZrO 2 particles was bigger than the upper critical grain size so that the phase transformation of tetragonal to monoclinic phase would occur spontaneously during cooling process. The optimal hot-pressing temperature for this material system should be 1850 °C to obtain high performance of the ZrB 2–SiC–ZrO 2f ceramics. The flexural strength and fracture toughness were enhanced to 1086 ± 79 MPa and 6.9 ± 0.4 MPa m 1/2, respectively. The toughness mechanism was mainly attributed to densification, phase transformation toughening, crack deflection, fibers fracture, fibers pull-out and fibers debonding.