The invention provides a tail heat exchanger system for a waste heat boiler; the tail heat exchanger system comprises an oxygen extractor and a condenser; the condenser is provided with a condensate pump; the tail heat exchanger system also comprises a low pressure economizer, a flue gas-hot water heat exchanger and a bromine chiller; the outflow end of the condensate pump is connected with the inflow end of the low pressure economizer through a valve, the outflow end of the low pressure economizer is connected with the oxygen extractor through a valve, the outflow end of the flue gas-hot water heat exchanger is connected with the inflow end of the bromine chiller through a valve, the outflow end of the bromine chiller is connected with the inflow end of the flue gas-hot water heat exchanger through a valve, the outflow end of the flue gas-hot water heat exchanger is connected with the inflow end of the low pressure economizer through a valve, and the outflow end of the condensate pump is connected with the inflow end of the flue gas-hot water heat exchanger through a valve. The tail heat exchanger system not only is good for operational safety of a unit, and can also make effective use of flue gas waste heat, energy utilization rate is increased, and economy of a power plant is improved.