This paper delineates the evidential system of Nuosu Yi, which is found to be formed of a reported evidential and an inferred evidential. We first describe the semantics of the two evidentials in Nuosu Yi and the interaction between them in terms of double evidential marking. Then we analyze the reported evidential by examining its relation to the verb of speech and (in)direct speech, and demonstrate how reported speech expressions give rise to the reported evidential. Finally, two syntactic tests are used to draw a clear-cut line between the epistemic modal and the inferred evidential in Nuosu Yi.