The performance of metamaterial absorbers can be affected by the incident angle of electromagnetic waves, and it is difficult to design metamaterial absorbers with wide-angle stability. The traditional method relies on artificial design and optimization, which limited by its difficulty and long cycle. According to the target design’s characteristics, we design a wide-angle and high-absorptivity metamaterial absorber based on the improved particle swarm optimization algorithm. Dynamic weights and Gaussian errors are added to resolve the problem of weak local search ability in the later stage of binary particle swarm optimization algorithm. To achieve wide-angle and high-absorptivity characteristics of the absorber, the improved binary particle swarm optimization algorithm is used to optimize the structure of discrete metal blocks coded with 0 and 1 on the surface of the absorber. The simulation results show that the designed metamaterial absorber has a high absorptivity of greater than 90% from 9.4-13.3 GHz, and perfect absorption, i.e., absorptivity exceeds 99%, is obtained in the broadband of 11.6-12.6 GHz. Moreover, the absorption remains above 80%, even for the incidence angles of up to 60° under both transverse electric and transverse magnetic polarizations. This design method overcomes the shortcomings of the traditional design method and demonstrates the unique advantages of on-demand design without human intervention in the design process. This technique has broad application prospects in related fields.