1. A fluorescence microscopic imaging method, comprising: after a to-be-detected sample plate is placed, lightening, according to an experimental requirement, at least one monochromatic fluorescence excitation light source with a same color among a plurality of monochromatic fluorescence excitation light sources as a target light source, wherein monochromatic fluorescence excitation light emitted by each of the plurality of monochromatic fluorescence excitation light sources obliquely enters a preset detection region of the to-be-detected sample plate; collecting, at a side of the to-be-detected sample plate facing away from the target light source, fluorescence of particles within the preset detection region excited by irradiation of monochromatic fluorescence excitation light emitted by the target light source, and magnifying the preset detection region a preset number of times; filtering the excited fluorescence of the particles within the preset detection region; and acquiring a fluorescence image of the preset detection region.