Abstract: In this study, the ms-2 strain with high cellulase activity was screened and identified from mangrove sediments samples. It is identified as a strain of Bacillus subtilis according to its morphological, physiological and biochemical characteristics and 16S rDNA sequencing result. The study on the enzyme producing properties found that the cellulase produced by the ms-2 strain was extracellular enzyme rather than membrane anchored enzyme. The enzyme presented good thermophilic activity and high activity in weak acid condition and produced the highest activity of 0.655 7 U/cm³ under the optimal conditions of 65 ℃ and pH 6.0. In addition, the enzyme activity showed no significant difference in 1 mmol/dm3 Cu2+, and significant inhibition in 1 mmol/dm³ Mg²⁺、Zn²⁺、Fe³⁺ and Mn²⁺, respectively. The enzyme activity was inhibited by 29.96% by Mn²⁺ while it showed more and less inhibition by Cu²⁺、Mg²⁺、Zn²⁺ and Fe³⁺, respectively. Enzymatic hydrolysis of cellulase in industrial applications usually needs to be carried out at 55-60 ℃. Thermophilic cellulase obtained not only is suitable in such temperature environment, but also can maintain a high level of enzyme activity. Moreover, the feature of less sensitive to Cu²⁺、Mg²⁺、Zn²⁺ and Fe³⁺ is favorable for the potential industrial application.