The genus Mullederia (Acariformes: Stigmaeidae) are free-living predatory mites with six species known in the world. In this paper, we describe and illustrate a new species, Mullederia hainanensis sp. nov., from deciduous broad-leaved plants and evergreen broad-leaved plants in Hainan Province, China. Moreover, an identification key is provided for the known species of this genus.