Flexible substrates are becoming more important in the printed circuit board and display industry. The flexible circuit boards can be thinner and lighter than rigid board, and can be flexibly and easily assembled into high level electronic product. The era of ink-jet fabrication is coming due to its low cost, high throughput and the feasibility of manufacturing on flexible substrate. The innate of ink-jet printing in non-contact characteristic and digitalization of patterning make it become a bright star in future manufacturing. In this paper, an evaluation of the possibility of ink-jet fabrication in reel-to-reel system was prepared for (a) the comprehensive stability occurred in jetting behavior, it included the stability of electrical firing control, ink back pressure control and ink temperature control. (b) The need of surface property and uniformity prior to ink-jet printing, especially for polyimide substrate and its treatment. (c) The image compensation of extension due to the reel-to-reel process. (d) The quality deterioration by the acoustic disturbing while high-speed flying of substrate relative to print head. (e) The integrated line flow design and compromise of speed and performance. Specially, the working surface of the substrate is kept out of contact with each transmitting roller to avoid the pollution in this continuous roll-to-roll circuit fabrication system by ink-jet printing. This design is important for modular process flow.