The just-noticeable differences of visual gloss on reflective prints is studied in this paper. There exists no established standard viewing condition to study gloss as the Standard Observers condition when examining color. Hence, the normal viewing distance with free tilting angles at one direction is proposed as the viewing condition to evaluate gloss. The method of constant stimuli with forced choice procedure is chosen to conduct the psychophysics experiment. The sample space is divided into five groups in terms of the measured gloss reading, and observers are asked to compare with the reference in each group. Data is analyzed based on the assumption of Gaussian psychome-tric model, and a set of visual gloss differential threshold is obtained. Two experiments are also done on cyan and magenta print samples for comparison.