The Manshuiwan dialect of Yi language is used by the Muhesu subgroup of Yi people in the Anning River Valley of Sichuan Province. This subgroup is distributed mainly in Mianning, Xichang, Xide, Yuexi, Dechang and other counties and cities in Liangshan Yi Autonomous Prefecture, as well as Shimian County in Ya''an City, with a population of about 50,000. Research on its ethnic origin and language has significant academic and practical value. Our paper targets the Manshuiwan dialect in Mianning County and conducts a preliminary study on its phonology, vocabulary and grammar. It’s found that while this dialect retains the characteristics of the Shenzha, Suodi and Yinuo dialects of Yi language, it also has features of glottalization of vowels and labiodentalization of consonants. Mixed loanwords account for a significant proportion in its vocabulary, reflecting the cultural integration of Han and Yi ethnic groups. Its grammatical features include the SOV word order and the postposition of noun modifiers, etc. These linguistic features can provide important data for comparison of languages among Yi subgroups and for study of ethnic group culture.