Consumer waste of cotton cellulose is receiving increasing attention. In this study, in order to recycle waste cotton cellulose fibre into ultrafine powder efficiently, a compact process containing sulfuric acid treatment and stone milling was examined. Scanning electronic microscopy (SEM) and atomic force microscope (AFM) were used to study the morphology of the original cellulose fibre, acid modified fibre and milled cellulose powder. The particle size, crystallinity and strength loss were also explored. The results illustrated that the fibre strength can be largely reduced by acid treatment and high temperature and the crystallinity of the fibre decreased after stone milling. Ultimately, the production efficiency and the output of the micron dry cellulose powder were greatly improved. About 1 kg dry ultrafine powder with particle size around 40 mu m was achieved in 1.5 h by stone milling in laboratory. This method shows a great potential for industrial application in the future. (C) 2020 Elsevier B.V. All rights reserved.