A highly active nitrogen-doped pitch-based spherical activated carbon catalyst (PSAC-N) is synthesized through a nitrogen-doping treatment and used as a nonmetal catalyst for acetylene hydrochlorination. The conversion of acetylene on PSAC-N exceeds 68 % and the selectivity of vinyl chloride is over 99 % at a temperature of 250 °C, an acetylene gas hourly space velocity of 120 h−1, and a feed volume ratio V(HCl)/V(C2H2) of 1.15. DFT calculations performed with Gaussian 09 program package reveal that the active site of PSAC-N has a N-6v (quaternary nitrogen bonded between two 6-membered rings) structure. A seven benzene ring unit model is used in the DFT study. In addition, the reason for inactivation for PSAC-N catalysts is discussed. Of all the adsorption energies obtained, the adsorption capacity of hydrogen chloride on PSAC-N is the highest, which indicates strong ability for acetylene hydrochlorination. The reaction mechanism is determined, and the reaction energy of N-6v(7) calculated as 236.2 kJ mol−1.