Abstract: Heat dissipation performance of the cast busbar is very important for safe operation of the cast busbar. Based on the optimizations of boundary conditions and heat loss calculation methods, temperature field calculation model of a 1 600 A cast busbar was established. The temperature field distribution in the cast busbar joint zone and influences of different factors, such as thermal conductivity of cast material, surface convective heat transfer coefficient of the busbar and structural parameters of the busbar row etc., on busbar heat dissipation were studied. The results show that the temperature of L2 phase main circuit is the highest in the internal area of the busbar joint, while the temperature of the center of the lower surface is the highest in the surface area, which are the key operation parameters of the busbar. The heat dissipation in the busbar surface area can be significantly enhanced by increasing the surface convective heat transfer coefficient and cross-sectional area of the busbar, decreasing the ratio of busbar row width and thickness, while the heat dissipation in the busbar row area can be significantly enhanced by increasing the thermal conductivity of casting material and cross-sectional area of the busbar.