In the utilization of acetylene as the raw material in chemical engineering, the understanding of its pyrolysis mechanism is a key issue to avoid its explosion. The ReaxFF molecular dynamics method has been employed to explore the pyrolysis process of acetylene at different temperatures and pressures, and the reaction mechanism and kinetic model were determined. The simulation results showed that the pyrolysis mechanism of acetylene can be divided into three temperature ranges. The simulation results further revealed the influence of pressure on the pyrolysis of acetylene. Through the identification, quantification and evaluation of the reaction trajectory, the reaction network for the pyrolysis of acetylene to generate species below C10 is obtained.The kinetic model of acetylene pyrolysis has been revised and perfected, and the results obtained are in good agreement with the experimental data.