Mallotus bullata M.T.An & J.H. Yu sp. Nov. (Euphorbiaceae), a species new to science discovered in Guizhou, China, is described and illustrated here, along with its phylogenetic position among other Mallotus species. Morphological, micro-morphological, and molecular evidence is presented as attestation of its novelty. The new species morphologically resembles M. philippensis var. reticulatus and M. philippensis, but it clearly differs by having leaf surface bullate, absence of coarse serrations on leaf margins, lateral veins reticulate near margins, sepals in male flowers 5, polygamous flowers, pollen grains 3 apertures with have obvious protrusions in the apertures, abaxial leaf epidermal microhairs 1-8 mm long. Molecular phylogenetic analysis (BS = 100% / BS = 96%, PP = 1 / PP = 1) provides strong evidence supporting M. bullata as a new species within the genus Mallotus.