Abstract: To address the challenge that shock wave attenuation in multilayer composite target plates under explosion load is complex and difficult to predict quantitatively, a multilayer composite target plate consisting of polyurethane, 45# steel, and ultra-high molecular weight polyethylene (UHMWPE) was taken as the research object, and the construction of a dimensionless prediction model for shock wave attenuation along the thickness direction of the composite target plate as well as the influence of dimensionless parameters were systematically investigated. Based on the theory of shock wave propagation in composite target plates, contact explosion experiments and numerical simulations under two typical working conditions were carried out, and interlayer peak pressure data were acquired. Then, by combining dimensional analysis with the π theorem, a dimensionless prediction model for shock wave attenuation along the thickness direction of the composite target plate was derived and established. The results show that the relative errors between the contact explosion experimental results and the numerical simulation results are all within 10%, indicating that the established numerical simulation possesses reliable accuracy. The coefficient of determination (R²) of the constructed dimensionless model is 0.9582, and the residuals exhibit a random distribution with no systematic bias, demonstrating excellent fitting precision. In the attenuation model, the dimensionless transmitted pressure shows a monotonically increasing trend with the increase in the charge length-to-diameter ratio, and decays exponentially with the increase in the thickness of the multilayer composite target plate. These research conclusions are of great significance for the conceptual design and lightweight optimization of blast-resistant multilayer composite target plate structures.