The invention discloses a floating sphere immunofluorescent staining method and a staining device, belonging to methods for coloring a sample for test. The staining method comprises the following steps: separation of spheres from a culture medium, fixing by stationary liquid, adding of Triton X-100 transparent cells, closing by confining liquid, adding of an interest protein-resisting primary antibody working solution, adding of a primary antibody-resisting fluorescent secondary antibody working solution, and cell nucleus staining by DAPI dye liquor. The staining device comprises a cell chamber and a staining sleeve part arranged at the outer part of the lower end of the cell chamber in a sleeving way. The floating sphere immunofluorescent staining method has the advantages of high efficiency, simpleness, convenience and the like, an antibody usage amount is reduced, experiment cost is reduced, manpower and time are saved, an accurate and reliable experiment result is obtained on the basis that a fundamental principle that immunofluorescent staining is not changed and specially training experimenters is not needed, sphere loss in an experiment operation process is avoided, an experiment success rate is increased, and the efficiency is improved.