A new design of ink tank for the ink supply system of thermal ink-jet printer was presented in the paper. Some past and current designs of ink tanks for thermal inkjet printers were reviewed first in the paper. At the mean time, some comparisons of them were done for analysis. Hence, the fundamental design principles (nondimentional similarity) have been applied to explore what geometrical properties would be defined as the good configuration of ink reservoir. It's found that one tall and narrow appearance of ink tank, as first feature, could be preferred to offer many advantages, such as compact spacing, ease for replacing, good readability for ink level, and so on. In addition, one new feature of end leg was added onto the present design in order to minimize the remaining ink, which can be useless for ink supply. Another feature of simple visible ink level was also offered for users to show how much ink was remained all the time. The performance of ink supply, as one example, was demonstrated in the end. The new presented tank here will meet basic needs of ink supply and further own many advantages, including compact spacing, visible ink level, minimum residual ink, and so forth.