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.