The heating process in Direct Current (DC) electromagnet coils causes rapid temperature increase in their constituent components. This phenomenon is particularly concerning as it may cause accelerated aging and even melting of insulating material components. This, in turn, has a significant impact on the coil’s service life. The design of the electromagnet coil exerts a substantial influence on its temperature rise. Unreasonable design parameters can have a substantial impact on the coil’s power consumption and cost. Currently, coil design parameters are predominantly selected through experiential methods, highlighting the need for improved design methodologies. This paper proposes a novel approach to overcome this challenge. It involves the consideration of temporal variations in thermal loads and boundary conditions, leading to the construction of a simulation model that delineates the coil’s temperature field. Subsequently, a multi-objective optimization design method for the coil is presented, taking into account the inherent spatial constraints of the electromagnet. This method facilitates the identification of the optimal coil design parameters, enhancing the efficiency and reliability of the electromagnet. The temperature rise simulation of the optimized coil is conducted, and through theoretical analysis and simulation verification, the temperature rise of the coil is reduced, thereby improving the coil’s overall benefits in terms of power consumption and cost. Finally, a temperature rise test bench for the coil is constructed for experimental verification, and the results provide a guidance for the optimization of the electromagnet coil and have certain engineering application value.