The invention discloses a preparation method of a 
flue gas bipolar 
heat exchanger for a radiant tube burner, which comprises the following steps: respectively and independently assembling and 
welding three assemblies, namely an internal finned tube 
assembly, a 
flue gas cavity 
assembly and an air inlet connecting tube 
assembly, respectively carrying out airtight detection after 
welding, and then, firstly sleeving the 
flue gas cavity assembly into the internal finned tube assembly; and then the 
smoke cavity assembly is connected with the connecting 
flange, on the outer side of the connecting 
flange, the 
flange of the air inlet connecting 
pipe assembly is connected with the outer side of the connecting flange, and assembling can be completed. The manufacturing process is simple and efficient, the working procedures do not restrain each other, production is flexible, and the situation that the whole working procedure is affected due to stagnation of one working procedure is avoided; the delivery state of finished products is flexible and variable, and the finished products can be transported to an installation site after being assembled in a manufacturing factory and can also be packaged and transported in a classified mode according to assemblies and flexibly assembled on the installation site; the technical key points are clear and controllable, and the production efficiency and the product quality are greatly improved; and the productivity efficiency in the process assembling and 
welding process is high, and 100 machines can be achieved by 5 persons per 16 shifts.