The invention relates to a Devosia sp. fjfst-330 strain and a method for preparing kappa-carrageenanase by using the strain. The strain has been registered and collected at China Center for Type Culture Collection on December 25th, 2013, and the collection number is CCTCC M2013704. In a fermentation medium composed of a carbon source, a nitrogen source and inorganic salts by using the strain as the seed, the activity of the kappa-carrageenanase is up to 104.4 U/ml under optimized culture conditions. The method for preparing the kappa-carrageenanase comprises the following steps: salting out the fermentation liquor by ammonium sulfate, centrifugating, collecting the precipitate, dialyzing, passing the dialysate through an ion-exchange column and a gel column, and carrying out freeze-drying to obtain the kappa-carrageenanase dry powder.