【Objective】To characterize genetic diversity levels of Cacopsylla citrisuga Yang & Li collected from two regions of Yunnan Province. 【Method】 The samples of C. citrisuga from Ruili city and Shiping county were identified by the gene barcoding of the mitochondrial cytochrome C oxidase subunit I (COI). The phylogenetic tree and genetic distance were obtained.【Result and conclusion】 Two haplotypes of C. citrisuga, C1 and C2 were identified. C1 was the only haplotype of the populations from Ruili city, while C1 and C2 both existed in the population from Shiping county. Unlike other previous studies of insects, the COI-based genetic diversity of C. citrisuga was extremely low, with the maximum sequence divergence being only 0.16%. The COI fragment can be used to distinguish C. citrisuga from the other four Cacopsylla species successfully.