The ink-jet printing has the benefits of simple process, low ink running cost, easy to expend to large size panel application, as it was claimed prior years. But down to for real fabrication, the ink recycling and the service treatment are a big challenges to be solved. Different ink properties should be carefully designed its recycling process and minimum waste of ink during head cleaning, to save the ink expense in manufacture. This article discussed five issues in ink flowing: (a) the materials compatibility for ink and piping (b) the reduction process about low air bubble (c) pressure oscillation, (d) the flowing behavior with temperature change to high viscosity ink, (e) the mechanism for ink recycling and maintain,. In our calculation, the ink running cost will save 50% with the recycling device and refreshing mechanism, the replace time of ink can extend up to 4 weeks, and is possible used for real mass production.