The invention is related to a cartridge adaptor which comprises a first dual-barrel cartridge, a housing, an adaptor and a second dual-barrel cartridge. The first dual-barrel cartridge comprises two openings and is disposed in the housing. The housing comprises a first fastening component. The adaptor has two inlets which opposite to the two inlets. The two inlets are respectively mounted into and communicate with the two openings of the first dual-barrel cartridge. The two outlets communicate with the two inlets. The second dual-barrel cartridge comprises two openings and a second fastening component which is complementary to the first fastening component of the housing. The two openings of the second dual-barrel cartridge communicates with the two outlets of the adaptor. The invention prevents the remaining unmixed component substances from oozing out of the two inlets or the two outlets of the adaptor during the transfer process of the remaining component substances.
