The invention discloses an ink-jet printing system and a deviation rectifying method for the ink-jet printing system. The ink-jet printing system is specifically composed of a printing unit, a monitoring module and deviation rectifying software, wherein the printing unit comprises a printing module and a printing module beam, the total width of a nozzle on a printing jet head is larger than the width of an image to be printed, the monitoring module comprises a photographing device and a supporting beam, the supporting beam stretches over a printing medium and is located on one side, in the paper discharging direction, of the printing module beam, the supporting beam is provided with the photographing device, when finding that the position of the photographed image deviates, the deviation rectifying software selects the jet head for printing the deviation image and carries out real-time X-axis or Y-axis deviation adjustment on ink discharging data of the selected jet head, an FPGA in a jet head control plate directly transmits the adjusted ink discharging data to the jet head, and the image with printing deviation is adjusted to the correct printing position. The ink-jet printing system is applied to an assembly line, the deviation problem occurring in the image printing process can be found in real time, adjustment is carried out in time, printing will not be interrupted, and meanwhile the printing effect of fast jet drawing is ensured.