Abstract: In order to make ink presetting technology of digital printing process based on JDF more accurate,according to the ink transfer of offset press,analysis of the relationship between key opening and specimen page density value is conducted,and the curve of the relationship is established with the investigation in practice.The algorithm of the relationship and the ink presetting are implemented.Compared with the traditional ink controlling technology,this technology shortens the adjustment time when the machine starts,quantifies the data of ink presetting,improves the printing efficiency,and reduces the printing cost.