A mobile advertisement system mounted on a back window of a vehicle using suction cups is presented according to aspects of present disclosure. In certain embodiments, the mobile advertisement system connects wirelessly to a mobile advertisement server, sends its GPS location updates periodically to mobile advertisement server, receives advertisements and delivery instructions from mobile advertisement server in response to the GPS location updates sent, displays advertisements on the display screen of the mobile advertisement system according to the corresponding delivery instructions when at least one automobile is detected, and transmits delivery confirmations to mobile advertisement server after each advertisement is displayed according to the corresponding delivery instructions. A video camera detects whether there are any automobile behind, and mobile advertisement system will not display advertisements when there is no automobile behind. brightness of advertisement display is in directly proportional to light intensity outside detected by a light sensor.