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In order to obtain the new cellulose-degrading bacteria at normal temperature, a bacterial strain named as 18B with cellulosedegrading ability was isolated and purified from garden compost in this study. Congo red staining experiment and filter paper degradation experiment were conducted to verify its cellulose-degradation ability. 16S rRNA sequence alignment and whole genome alignment confirmed that it belonged to the genus Olivibacter, and was the closest to Olivibacter jilunii 14-2AT . Further comparative physiological and biochemical characterization revealed differences with O. jilunii 14-2AT in terms of growth temperature, oxidase and glycolysis. The strain 18B grew in the range of 12-48℃, and the optimal growth temperature was 30-37℃ . O. jilunii 14-2AT grew at 4-42℃ . Strain 18B was positive for oxidase and negative for glycolysis, while O. jilunii 14-2AT had no oxidase activity and was positive for glycolysis. Combined with the results of the genomewide covariance alignment, it was known that strain 18B had a certain evolutionary relationship with O. jilunii 14-2AT . The cellulose-degradation ability was found that the cellulase activity of 18B was up to 82.14+0.99 -9.90 U/L at 37℃, 200 r/min until the 5th d. Meanwhile, the enzyme activity could be maintained without degradation under the incubation conditions with sodium carboxymethyl cellulose as the only carbon source and only inorganic nitrogen source added. O. jilunii 14-2AT had no cellulose degrading ability and could not survive in a culture environment where sodium carboxymethylcellulose was the only organic carbon source. The results of whole genome sequencing showed that there were cellulase genes in the genome of strain 18B. The cellulase genes were heterologous expressed in Escherichia coli, and the degradation ability of the expressed products was tested. The results showed that the cellulase genes were active. The above results finally identified strain 18B as a new physiological strain of O. jilunii with cellulase activity. [ABSTRACT FROM AUTHOR]