The invention discloses a 40-thousand-ton hard carbon black reaction furnace and a production process of carbon black. The carbon black reaction furnace comprises a combustion chamber, a venturi tube, a reaction chamber, and a quench zone. The uniquely designed combustion chamber of the reaction furnace ensures that the distribution of the temperature field of the carbon black production is more reasonable, the appropriate angle, length and inner diameter of the venturi tube ensure that raw oil is fully vaporized and sheared on the venturi tube part; and the reasonably designed reaction section and the matched quench zone ensure that the carbon black cracking reaction can be performed quickly, and the side reaction can be inhibited. Coal gas or natural gas is used as a fuel, the range of the raw oil is wider, the production capacity of the carbon black is high, unit consumption is low, a small amount of polluted product is discharged and the quality of the carbon black is high.