An assembling structure for a filtration set includes a filter set having a plurality of filter cases, the filter cases assembled together, an assembling portion extruded on an outer surface of each filter case, the assembling portion extending from a top to a bottom of each filter case, at least one assembling plate having two ends which are respectively extruded from each side of the assembling portion and the outer surface of the corresponding filter case, the assembling plate having a positioning block at a periphery thereof, a plurality of bolts used to be inserted through the positioning block of each filter case. Wherein, a user can assemble the filter cases together via the positioning block and the bolt.