One type of battery quick-change system of electric passenger car chassis based on the Cartesian coordinate robot, including electric changing platform, and this platform, quick-change robot and charging rack along the same straight line; the quick-change robot comprises the battery tray and the Cartesian coordinate robot of four degrees of freedom, the Cartesian coordinate robot is associated with the X-axis driving motor, the Y-axis driving motor, the Z-axis up-down motor, the battery tray is connected with the R-axis driving motor; each of driving motors is connected with the corresponding encoder, and each of encoders is connected to the corresponding drive; there are equipped with a distance measuring sensor on the battery tray, and the corresponding limit switches on the both ends of each two-track rack; the drive, each limit switch and the distance measuring sensor of each driving motor are connected with the control system.