Bremsstrahlung diode is an important device for obtaining large area uniform bremsstrahlung field in laboratory. In this paper, based on Monte Carlo method, a model of single and double ring parallel electron beam bombarding tantalum target is established to simulate the process of bremsstrahlung field generated by ring diode. The electron beam energy is 1.5 MeV, the tantalum target thickness is 200 μm, and the dose of bremsstrahlung field generated by a single ring electron beam 10 cm behind the target is simulated by detector counting method. For single-ring diode structure, the inner diameter of the ring is the main factor affecting the bremsstrahlung field uniformity behind the target, and the larger the inner diameter, the worse the central dose uniformity. Compared with the inner diameter of the ring, the ring width mainly affects the dose of the radiation field, but has little influence on the uniformity. When the inner diameter of a single ring is 19 cm and the outer diameter is 20 cm, a uniform radiation field with a maximum area of 2290.221 cm² can be obtained. When the inner diameter of a single ring is 19 cm and the outer diameter is 20 cm, a uniform radiation field with a maximum area of 2290.221 cm² can be obtained. The double-loop diode structure can obtain a larger area of uniform radiation field than the single-loop structure. However, the variation of the outer ring diameter leads to multi-level peaks in the dose distribution of the radiation field, which also affects the homogeneity of each region of the radiation field. The simulation results show that by adding a concentric outer ring with an inner diameter of 43.5 cm and an outer diameter of 44.167 cm to the outside of the single ring structure, the radiation field area meeting the uniformity requirement can be increased to 7238.229 cm².