Abstract: Achieving efficient plane wave loading on the test specimen is one of key technical issues to be addressed in the design of blast load simulator. In order to develop a safe, economical, and reusable blast wave simulator, numerical simulations were conducted. Based on existing testing device, large-scale shock tube test data, and LS-DYNA software, the numerical models of blast wave propagation in blast wave simulators were established. A quantitative method for assessing the uniformity of overpressure load on the loading area was proposed. Numerical analyses were performed to investigate the influence of the shape and length of expansion sections and the length of conditioning sections on the uniformity of overpressure loads on the loading area. The wall thickness of expansion and conditioning sections and the spacing and height of stiffeners, were numerically optimized to achieve an optimal geometric and structural design. It is found that the established numerical model can reproduce the blast wave propagation accurately and the prediction results show good agreement with the testing data. Taking the errors of overpressure peak value and arriving time as factors, a quantitative evaluation method of overpressure load uniformity on the loading area is achieved. Considering the balance between technical and economic factors, the developed blast load simulator is designed with a symmetrically configured expansion section with a length of 3 m, while the conditioning section length can be extended as much as practically feasible depending on the investment. Based on the numerical results, the wall thickness of both the expansion and conditioning sections is determined to be 30 mm, while the height and spacing of the stiffeners are set at 150 mm, respectively. Experimental validation confirms that the design meets the requirements of the blast load and structural blast resistance, demonstrating the simulator suitable for component-level blast tests.