Friction conditions have important influence on the metal forming process. This is even more significant in microforming because of size effect. Friction size effect was studied in this paper. The specimen material was copper alloy T2 which was thermally treated at 873 K for 12 h in nitrogen atmosphere. The specimens were manufactured by wire cutting with initial width of 8, 4, 2, and 1 mm, and length of 80 mm. The experiments were carried out at room temperature on a universal testing machine under four kinds of lubrication conditions. The results showed the friction size effect was not found without lubrication. However, the friction size effect took place when lubricated with soybean oil, castor oil, and petroleum jelly. The friction coefficient increased distinctly with the miniaturization of the specimen size. The reason for this phenomenon was also discussed in this paper.