The invention relates to an internal combustion engine exhaust temperature control device capable of achieving sectional pressure and temperature adjustment. The internal combustion engine exhaust temperature control device is mainly composed of a temperature and pressure adjustor, a control unit and various electromagnetic valves. The temperature and pressure adjustor can be used for achieving sectional pressure and temperature adjustment so that a heat storage working medium can be basically kept near a preset target state, meanwhile, high temperature and high pressure are maintained in a state constant box, and the capability of heating low-temperature waste gas is achieved all the time. The heat storage working medium in the temperature and pressure adjustor can absorb and store heat of the high-temperature waste gas, after subsequent low-temperature waste gas passes through, heat can be transferred to the low-temperature waste gas again, and therefore control over the temperature of the waste gas is achieved. A control module controls a path of the waste gas according to a signal of a waste gas temperature sensor, when the temperature of the waste gas is in an efficient temperature window required by postprocessing, the waste gas directly flows into a postprocessor through a waste gas direct-through pipe, and when the temperature of the waste gas is not in the efficient temperature window required by postprocessing, the waste gas flows through the temperature and pressure adjustor to be subjected to temperature adjustment and then flows into the postprocessor.