Micranisa Walker, 1875 is a genus of non-pollinating fig wasps in the subfamily Otitesellinae (Chalcidoidea, Pteromalidae). Ten world species belonging to Micranisa have been recorded. In this paper we describe a further species, Micranisa trispina Ma & Yang sp. nov., associated with Ficus curtipes Corner (Ficus subsection Conosycea, section Urostigma, subgenus Urostigma) from Xishuangbanna, Yunnan, China. A key to described species of Micranisa is provided.