Abstract: A new flat strip-insert with elliptical teeth and notches was developed to solve the problem of rapid fouling growth and reduced heat transfer coefficient at a low flow rate in heat transfer tubes. The notches were distributed and staggered on both sides of the strip. An oblique tooth followed each tooth. Thus, the fluid flowed spirally. It was just like the flow when twisted strip with oblique teeth was inserted in tubes. Such spiral flow enables the flat strip-insert to self-rotate and remove fouling on tube wall at a low flow rate. Much strong vortex was produced behind each elliptical tooth, which were distributed uniformly, so convective heat transfer was enhanced greatly. The tube side heat transfer film coefficient increased by two times in comparison with that without any insert. The enhancement was more than simple twisted strip by over 5 times. The flow resistance coefficient was much higher than that of simple twisted strip, but the overall equipment resistance was not high and was in the range of engineering application. The new flat strip- insert with elliptical teeth and notches can be made through injection molding. The manufacture cost was low and the quality was quite good. It can be put into mass production and used widely in heat transfer equipment.