Results of experimental research on diamond surface metallization with electrolyse plating and vacuum plating show that strength, thermal stability and penetration rate of metallized diamond are much better than that of nonmetallilized diamond, and performances of diamond plated with Ti are the best among all plated diamonds. Carbon in carbides such as TiC, Cr 2C 3, formed on diamond surface obtained with vacuum plating comes from diamond, but not from graphite. Therefore, vacuum plating is a prospective diamond surface treatment method.