Sugarcane mosaic disease (SMD) caused by Sugarcane mosaic virus (SCMV) occurs in many sugarcane-growing countries and is one of the most important sugarcane diseases.In this study,we investigated 78 SMD isolates from 44 with typical mosaic virus symptoms.The samples were collected from Southern China including four provinces: Guangxi,Yunnan,Hainan,and Guangdong,which are four major commercial sugarcane-producing provinces covering 85% of sugarcane planting zones in China.We found that Sorghum mosaic virus (SrMV) was more prevalent than SCMV and Sugarcane streak mosaic virus (SCSMV).Phylogenetic analysis divided the isolates of SrMV into three subgroups (Ⅰ,Ⅱ,and Ⅲ) presenting its diversity in China.SrMV Ⅰ and Ⅲ were dominant in Guangdong and Guangxi,but SrMV Ⅱ didnt showed close relation in geographical distribution.SCSMV was first detected in in Yunnan indicating that this virus had been transferred from a quarantine zone.The co-infection of SrMV and SCSMV was only detected in Saccharum hybrid (YN-bs-9).The popular sugarcane cultivar ROC22 was infested with all these three subgroup types of SrMV.We choose the most prevalent sugarcane mosaic virus strain and infected host sugarcane ROC22 also belongs to the biggest growing cultivar in China.One SrMV isolate from ROC22 (HN-lg-1) was visualized as long rod-shaped (0.7-1.6 μm) under electron microscope and its coat protein was confirmed by western blotting and MALDI-TOF-TOF.DNA and amino acid sequences revealed an unusual viral-preference on codon usage.This study provides insight into the species diversity and geographical distribution of SMD,and it will also provide the basis for its identification,prevention,and control.