The signatures of the paintings are relating to the commercial of the oil paintings. At first, the artists regarded the signatures as a sign of propaganda in order to expand their influence and increase the order of the works by sign the name. With the passage of time, signing becomes the artists' practice.

According to historical records, signing appeared in the oil paintings as early as Albrecht Durer' works. Durer signed the combinations of the beginning two-letter A D on the oil paintings.

The artists' signatures are various, but generally signed in the corner which is inconspicuous. Some artists sign the name in the "props" or patterns, making it melted with the painting. Such as Holbein sign the name on the pieces of wooden board on the background tress in the 《ambassador's》. Delacroix's name is signed on the wooden ramp in the distance of 《liberty leading the people》. Xie Luof's name is signed at the right corner closed to the table cloth in 《Girl and the Peach》.

Chinese oil paintings usually sign the abbreviations of the phonetic alphabets. Modern artists directly sign name or spelling, the joint-user of the name, while sign the creative era and works the title on the back of paintings. Works need to specify the size, materials, creative era, the author and work units, detailed mailing address during exhibition. Some artists also often set a special tag on the oil painting or the corner to avoid imitation. The artists often use symbolizing the name to sign name. Like artist Mr. Hu Yichuan signed by "川" and easily to identify.