This paper is the first in a series on the genus Trachys Fabricius from China. Diagnostic characters and the unreliability of some characters commonly used by previous authors are discussed, and new diagnostic characters are proposed for taxonomic studies of this difficult group. Eight new species are described and illustrated from China: Trachys purpuratus Peng, new species; Trachys acuminatus Peng, new species; Trachys suichuanensis Peng, new species; Trachys fusiformis Peng, new species; Trachys ovalis Peng, new species; Trachys latus Peng, new species; Trachys lushanensis Peng, new species; and Trachys meilingensis Peng, new species.