In this paper, a flexible ultrawideband metamaterial absorber (MMA) with multiple perfect absorption peaks has been proposed and investigated. In this design, we choose the rubber as the dielectric layer to achieve flexibility and select the split square ring to reach multiple perfect absorbing peaks. For the simulation results, the three-layer absorber that reaches 90% absorptivity has achieved 3.87 to 10.84 GHz. Then, we propose a five-layer absorber for easy facilitation, whose absorptivity reaching 90% has achieved 3.78 to 9.85 GHz, and the absorption peak has reached 99.99%, 100%, 100%, and 99.99% at 4, 5.82, 8.46, and 9.71 GHz, respectively.