High-purity graphite was prepared from coal coke particles and high-temperature coal pitch, and its micro-structure characteristics and physical properties were measured and analyzed. High-purity graphite was used in the reduction furnace of the polysilicon preparation, which played the role of clamping the silicon rods, conducting electricity and transferring heat. Measures to improve production reliability and reuse rate of the graphite assembly in the reduction furnace were discussed. The results showed that the structure of the high-purity graphite samples was relatively smooth in general, and exhibited good similarity overall structure at different scales. The prepared high-purity graphite materials had outstanding physical properties: the bulk density of 1.84~1.88 g/cm3, the shore hardness of 55.2~62.4 Hs, the flexural strength of 33.9~45.6 MPa, the compressive strength of 66.3~78.8 MPa, the thermal expansion coefficient of 3.76×10–6/℃~4.08×10–6/℃, the electrical resistivity of 8.92~11.98 μΩ?m, and the ash content of 133~202 mg/kg, respectively. All the parameters of the samples were excellent. From the analysis of elemental composition, carbon element is the absolute main body, its weight content was between 88.71wt%~90.57wt%, and its atomic content was between 92.09at%~93.25at%. In addition to the matrix carbon, other elements are mainly O, S, Si, and Al. The weight content of O was between 7.15wt% and 9.79wt%, and the atom content was between 5.61at% and 7.57at%. Except for C and O, the content of other elements was lower, and the atomic content was lower than 1at%. In addition, the phenomenon of “bright spot” and “collapse of the silicon rod” in reduction furnace applications due to heterogeneous conductivity and heat concentration in the silicon cores was analyzed. By optimizing the structure of the graphite assembly, the reuse rate of the graphite cap was increased from 5.85% to 7.28%, the reuse rate of the graphite seat was increased from 7.95% to 9.01%, and the collapse rate of silicon rods was reduced from 14.22% to 4.43%. Consequently, the safe production in the reduction furnace was more effectively improved, the reject rate and the production cost of silicon rods were reduced, which demonstrated good application prospects of the coal-based high purity graphite in the field of the preparation of polysilicon.