Effects of SiC/HfC ratios on the ablation and mechanical properties of 3D C-f/HfC-SiC composites by precursor impregnation and pyrolysis (PIP) process were investigated systematically. Both strength (flexural and compressive strength) and modulus increase as the SiC/HfC ratio are improved. The compact and stiff HfC-SiC matrix in addition to the carbon fiber and PyC interphase with less reaction damage accounts for the improved mechanical properties of C-f/HfC-SiC with higher SiC/HfC ratios. Meanwhile, both weight loss and erosion depth of C-f/IfC-SiC are improved with the increased SiC/HfC ratios. Therefore, in order to balance the ablation and mechanical properties, an appropriate SiC/HfC ratio should be considered. (C) 2017 Elsevier Ltd. All rights reserved.