The lead based fast reactors often use integrated core design scheme, due to its compact structure, and the helical coil tube type once-through steam generators (OTSG) have been utilized in various reactors. In order to study the flow and heat transfer characteristics of the lead bismuth eutectic based coolant in the shell side of the helical coil tube OTSG in lead based fast reactors, a section-by-section solution method is adopted, and the wall heat flux fitting formula is used to simulate the flow field of shell side, with the help of FLUENT software. Finally, the correctness of the section-by-section solution method is verified, the flow and heat transfer characteristics of the shell side are analyzed, and the calculation data of velocity, temperature and pressure field are obtained. Its results lay a foundation for the next step of steam generator flow induced vibration analysis and high temperature stress calculation.