The invention discloses a method of preparing hard 
carbon felt. The method includes the following steps that S1, a mesh blank prepared from short-
cut pre-oxidized 
fiber by 
carding and air-laying is adopted; S2, phenolic resin with a 
high carbon residue rate is adopted as a precursor; S3, 
anhydrous ethanol is adopted as a 
solvent; S4, a PAN pre-oxidized 
fiber mesh blank is subjected to lamination and 
relay needle 
punching on a needle 
punching machine to the required thickness according to the 
process design. According to the method of preparing the hard 
carbon felt, the pre-oxidized 
fiber is adopted as a 
raw material, overall pre-oxidized fiber felt is obtained after 
relay needle 
punching and severs as a preform, and overall hard thermal-insulating carbon fiber felt is prepared through 
carbonization, impregnation, curing, graphitization and other processes; because the density of a material has large 
impact on the mechanical and thermal properties of the material, the density of the overall hard carbon fiber felt prepared by the method is only 0.16 g / cm<3>, the 
thermal conductivity of the overall hard carbon fiber felt at 1500 DEG C is 0.25 w / (m.k.), and both of the density and thethermal 
conductivity of the overall hard carbon fiber felt are lower than that of traditional solidified felt formed by bonding soft 
carbon felt and an interlayer, it is indicated that the main properties of the overall hard carbon fiber felt are better than those of the traditional carbon felt.