Laser-induced graphene has been widely used in the fields such as microelectronics，energy storage devices，and flexible wearable devices due to its convenient preparation，tunable physicochemical properties，and strong compatibility.The acquisition of high-quality laser-induced graphene is an important prerequisite for further promoting its application.This paper focuses on the carbonization process of laser-induced graphene.A molecular dynamics model based on the ReaxFF reactive force field is built.The carbonization process is analyzed by adjusting the control parameters of polyimide （PI） pyrolysis.The growth mechanism of graphene clusters is investigated based on the molecular configuration evolution and crystalline characteristics analysis.The simulation results indicate that increasing the reaction temperature or prolonging the reaction time helps increase the number of hexagonal rings in the products.Based on the simulation conclusions， high laser power and low scanning speed are used to prepare laser-induced graphene （LIG） supercapacitors，and favorable rate performance （70% initial capacity is maintained at a scanning rate of 500 mV·s^-1） and low equivalent series resistance （52 Ω） are achieved.