The effects of structural parameters on the acoustic characteristics of geometrically asymmetric folded plate as well as its structural parameter optimization were conducted numerically in the present study. The results indicate that the geometrically asymmetric acoustic metamaterial investigated in the present paper exhibits isotropic reflection and transmission characteristics. Compared to the plate spacing and material properties, the plate thickness, deflection angle and plate inner diameter are more sensitive to its acoustic characteristics. Additionally, based on orthogonal optimization design, the transmission loss of the investigated geometrically asymmetric acoustic metamaterial is improved significantly in the frequency range below 2500 Hz. The studies can provide guidelines for the design of geometrically asymmetric folded plate acoustic metamaterials.