There is direct relationship between study on character identification and distance between interface and user, in which there are two kinds of conditions including public interface, such as projection, and personal interface, such as personal computer terminal. Firstly we will study the relationship between character height and the distance between eyes and character under the condition of personal terminal using teaching software. Generally speaking, in the choice of font, the identification effect of equal linewidth, such as Arial and Arial black, is better than non- equal linewidth, such as Song typeface and Times New Roman. On the SUMSUNG- 971p professional 19 inch display screen, we use Arial font, black color, word width of B, switching space of 0.2B and white background. Basing on the above-mentioned conditions, 20 testing people with naked eyes or corrected visual acuity of 5.0 have had the vertical angle of view test. Through statistical analysis, character’s lowest identifiability requirement is as shown in the following table.