Corrosion failure accounts for a large proportion of the failure modes of shell-and-tube heat exchangers. In this paper, the three-dimensional watershed model of shell and tube heat exchanger is established, and based on the computational fluid dynamics (CFD) method, the flow and heat transfer of the fluid in the shell and tube heat exchanger are calculated by FLUENT software, and the temperature field, pressure field, gas-liquid two-phase distribution cloud chart and velocity field distribution vector diagram in the shell and tube heat exchanger are obtained. On this basis, the corrosion location and corrosion mechanism of shell and tube heat exchanger are analyzed.The results show thatthe erosion of fluid near the baffle plate and the formation and accumulation of liquid components aggravate the corrosion of the heat exchangerand the corrosion is affected by many factors.The corrosion location obtained from the analysis of numerical simulation results is roughly consistent with the corrosion location of field equipment. The corrosion analysis of shell and tube heat exchanger based on the flow field provides a theoretical basis for the corrosion protection of heat exchanger.