Abstract: Anode saturable reactor(ASR) is a key primary device for converter valves, and its temperature rise caused by electromagnetic losses during operation is significant and poses a threat to insulation thermal aging. Therefore, accurately analyzing the temperature rise characteristics of ASR and seeking optimization methods are of great significance for its state evaluation and product design. This paper first establishes an equivalent thermal path model based on the heating mechanism and heat dissipation path, and qualitatively analyzes the temperature rise characteristics of ASR in actual operation. Then, the three-dimensional equivalent model of ASR is established, and the parameters of solid heat transfer and air convection are set based on the principle of transient heat transfer. The simplified model of water cooling based on turbulence and real-time mixing hypothesis is further applied to simulate the process of water cooling and heat dissipation. The accuracy and efficiency are compromised, and the coupled finite element simulation of multi-physics simulation is carried out to quantitatively calculate the size change and spatial distribution of ASR temperature. Finally, combined with the temperature distribution law, the structural optimization scheme of the combination of iron cores with different cross sections is proposed. The simulation verifies that the maximum temperature difference between each core is reduced by 91.7% of the original temperature difference, and the maximum temperature of the epoxy resin is reduced by 3 ℃ under the premise of the same electrical performance, which provides a reference for the performance verification and parameter design of ASR.