Bismuth tungstate（Bi₂WO₆） was prepared by one-step solvothermal method and was then immobilized on sodium alginate（SA） to prepare gel microspheres. By simulating the dye Rhodamine B（RhB） that contaminates soil,the effects of the concentration of SA, the concentration of cross-linking agent, the amount of applied catalyst and the time of cross-linking on the photocatalytic performance of the Bi₂WO₆ were studied. In the concrete process of study, the techniques of XRD, SEM, EDS, FT-IR and TG were utilized to characterize the structure, morphology,functional groups and thermal stability of Bi₂WO₆ photocatalyst immobilized by SA, and its photocatalytic performance to rhodamine B（RhB） solution was hereby determined. According to the concrete results of orthogonal test,the finest conditions for the preparation of Bi₂WO₆ immobilized particles can be described as follows: the concentration of SA is 1.5%, the concentration of crosslinking agent is 1%, the crosslinking time is 2 hours, and the amount of Bi₂WO₆ is 0.6 g. The degradation rate of RhB can be reached to 96.81% under the condition of visible light for a duration of 90 min, while its activity remains still high after 4 repeated tests. Such kind of catalyst effectively deals with the issues concerning hard recovery and secondary pollution of powder materials.