Abstract: A composite filter cartridge (12), a composite filter cartridge assembly (1) and a water purification system (100) are provided. The composite filter cartridge (12) includes a filtration assembly, a first end cap (124) and a second end cap (125) disposed to two axial ends of the filtration assembly separately, and a taste filter cartridge (123) disposed in the second end cap (125). The filtration assembly includes a pretreatment filter cartridge (121) and a fine filter cartridge (122), the taste filter cartridge (123) is connected to a central water collecting pipe (1221) of the fine filter cartridge (122) and is located downstream thereof, a concentrated water channel (a1) and a circulation channel (a2) separated from each other are defined between the taste filter cartridge (123) and the second end cap (125), and the taste filter cartridge (123) is provided with a pure water channel (a3) therein.