The invention relates to a tubular heat exchanger smoke temperature automatic adjusting system. The system comprises a smoke heat exchanger, an electric precipitator, a heating medium water inlet adjusting valve and a heating medium water bypass adjusting valve; the smoke heat exchanger is arranged in front of the electric precipitator, a heating medium water inlet pipe and a heating medium water outlet pipe are connected to the smoke heat exchanger, the heating medium water inlet adjusting valve is arranged on the heating medium water inlet pipe, the heating medium water bypass adjusting valve is arranged between the heating medium water inlet pipe and the heating medium water outlet pipe, and the connecting position of the heating medium water bypass adjusting valve and the heating medium water inlet pipe is located on the side, away from the smoke heat exchanger, of the heating medium water inlet adjusting valve. The system has the beneficial effects that the outlet smoke temperature of the smoke heat exchanger of a tubular heat exchanger is automatically controlled, meanwhile, stable running of a heating medium water system is ensured, the pressure of a heating medium water pipeline is ensured, the system is easy to control, and stable in running, safety risks are reduced, and the performance of the tubular heat exchanger is improved.