The standard for digital print quality and its measurement technology is now under consideration, and uniformity evaluation should be an important and essential quality factor. The paper provides a practical quantitative measurement method for traditional visual assessment on uniformity, and proposes a simple and effective IUI index to evaluate the uniformity of digital prints through NPS curve of the printed flat areas and CSF of HVS. The validity of the IUI is demonstrated through its applications in the uniformity assessment of the digital prints.