The utility model discloses a double -barrelled formula flue gas sampling line of permanent high temperature, including the heat band, the sample gas trachea, heat preservation and rack, the heat band is including the power connecting wire and the duo gen alloy heater strip of electricity connection each other, the sample gas trachea is two sample gas tracheas, the heat band sets up between two sample gas tracheas, the heat band passes through high temperature adhesive tape fixed connection with the sample gas trachea, the sample gas trachea includes air inlet and gas outlet, the heat preservation sets up at the heat band, sample gas trachea and high temperature adhesive tape's surface and the tracheal air inlet of sample gas and gas outlet all are located the outside at heat preservation both ends, the heat preservation is by the interior glass fiber layer that includes in proper order outside to, woven mesh layer is compiled to anticorrosive coating and black, the both ends of heat preservation are through pyrocondensation pipe and sample gas trachea sealing connection, the inside of heat preservation is equipped with temperature sensor, the temperature sensor electricity is connected with temperature controller, the utility model has the advantages of the temperature control accuracy is high, and life is of a specified duration, the heat loss is little, stand wear and tear and durable.