The present invention relates to an ink cartridge, an ink cartridge assembly and a method for detecting the installation of the ink cartridge. A plurality of ink cartridges are detachably mounted on an inkjet printer including a light receiver and a plurality of apparatus electrical contacts which are commonly connected with a line, the ink cartridge comprises a container electrical contact electrically connected with corresponding apparatus electrical contact an information storage device, a light-emitting portion configured to emit light towards the light receiver, and a control portion configured to control the light-emitting portion to emit light, wherein, the control portion of the ink cartridge controls the light-emitting portion to emit light when receiving an emission instruction sent by the inkjet printer. Therefore, the stability of the ink cartridge installation detection can be fully guaranteed and the phenomenon of installation detection error can be avoided.