The invention discloses an automatic temperature control reaction kettle for synthesizing p-chlorotoluene. The reaction kettle comprises a lower-part stirring paddle, an upper-part stirring paddle, astirring shaft, a water drainage valve, a circulating water valve, a water pump, a controller 1, a heating water tank, an air inlet pipe, an electric valve, a water inlet pipe, a water outlet pipe, afirst water inlet valve, a second water inlet valve, a chlorine gas inlet, a gas distributor, a material inlet pipe, a liquid raw material inlet, a coil water inlet, a gas outlet, a safety valve, a coil water outlet, a motor, a motor reducer, a coil, a liquid outlet, a temperature sensing device, a reaction kettle body, a sealing cover, a sealing ring, a mounting mouth, a jacket, a jacket water inlet, a jacket water outlet, a hot water valve, a cold water valve, a cold water inlet pipe and a controller 2. An automatic temperature control device including the jacket and the coil is adopted by the reaction kettle, so that the problems of too low selectivity caused by excessively high reaction temperature and a too-low conversion rate caused by excessively low reaction temperature are solved,and meanwhile full contact of reactants are achieved through adoption of the two stirring paddles and the gas distributor.