Abstract: An ink cartridge for inkjet printers is disclosed. The inkjet cartridge comprises a case, an ink supply chamber, and an ink storage chamber. The ink supply chamber and the ink storage chamber are inside the case. An ink outlet is provided on a sidewall of the case. The ink supply chamber is connected or linked in a low position with the ink outlet and in a high position with an air vent. The ink storage chamber is connected or linked in a low position with the ink supply chamber through a first passageway and a second passageway; the second passageway is below the ink outlet but above the first passageway. The cartridge has a simple structure. It eliminates the need of air pump and provides constant supply of ink to the print head. It avoids ink overflow caused by the temperature change in the environment.