The sound absorption performance of single layer metal rubber (MR) material was theoretically investigated. The formulae were deduced to calculate the acoustic impedance rate and sound absorption coefficient for two kinds of basic single-layer absorption structure in rigid wall and with air layer. The flow resistivity is the main parameter to determine the sound absorption performance of MR material. The influence of the thickness of MR layer, flow resistivity and thickness of the air layer on the sound absorption performance of the two kinds of structures was analyzed. The method for calculating first resonant frequency for single layer structure MR material was presented. The results indicate that the optimization of thickness of MR material, flow resistivity and the thickness of the air layer is helpful to improve the sound absorption performance of the single layer structure MR material.