The aim of this work was to study the compression behavior of a mat reinforcement. The compaction stages of the dry and wet reinforcement and its relaxation over time as a function of several pressure levels have been characterized with a custom-designed bench. The compression behavior of the reinforcement can be modeled by a power law. The coefficients of the law are changing with the rupture of the fibers during compression. The study of the reinforcement compressibility enables an optimized composite manufacturing, to obtain materials without porosity and without increasing the thickness induced by a polymer excess.