Effects of particle size (A: d50=336.9μm, B: d50=123.5μm, C: d50=19.5μm, D: d50=2.21μm) and content (1wt%, 3wt%, 5wt%, 7wt%) of silicon powder on cold crushing strength (CCS), pore size distribution and microstructure of Al2O3-ZrO2-C refractories coked at high temperature had been investigated by means of mercury porosimeter, SEM, EDS, etc. The results indicated that particle size and content of silicon powder affected the cold crushing strength of coked specimens. It increased with the addition of silicon powder and its finer particle size. However, it decreased greatly when using too fine silicon powder. The particle size and content of silicon powder also impacted the phase evolution and microstructure of coked specimens, much more β-SiC whiskers constituted network structure and well distributed in specimens with reduction of their slenderness ratios when finer silicon powder was added, corresponding to that, the specimens pore size distribution range became narrower with smaller pore diameter, but β-SiC whiskers were distributed sparsely and the specific pore volume of small pores increased when much finer powder was added. It was worthly mentioned that some nitride could form in specimens with addition of appropriate particle size and content of silicon powder.