The invention discloses a novel flavobacterium strain, a cultivation method for the strain and application of the strain in the aspect of producing agarase. The provided strain which can be used for producing the agarase is flavobacterium sp. CGMCC NO.2342, and is specially characterized in that the strain can generate the agarase without agar, and 0.05 to 0.25 percent of agar powder or a certain carbon source can be added in a liquid culture medium. The provided method for producing the agarase cultivates the flavobacterium sp. in a fermentation culture medium; and the crude enzyme liquid of the obtained agarase can be continuously concentrated and purified, and also can be directly used for degrading the agar to produce agar oligosaccharide. The agarase produced by the strain has high activity, produces various agarase, and can be expected to form various series of agar oligosaccharide.