Abstract: Macronaemia yunnanensis is described as new to science.The type specimen is kept in the Forestry Department of Yunnan province.Macronaemia yunnanensis,sp.nov.(figs.1-4) Body elongate oval,weakly convex;pronotum and elytra yellow with black patterens as figured.Male genitalia,sipho swellen at median part and bifurcate at apex.Median lobe of tegmen boat-shaped with a convergent apex in lateral aspect,parameres of tegmen longer than median lobe.Length:3.5-4.5mm.width:2.5~3.0mm.Holotype♂,Anning,Yunnan,1800 M.Paratypc 5♂,4♀,Anning,Yunnan,1800 M.30-Ⅵ-1982,by Xiao Ning-nian.This new species is allied to Macronaemia hauseri(Weise),but is distinquished from it by the patterns and male genitalia.(Ⅰ) The patterns of pronotum and elytra of the new species are evidently different from Macronaemia hauseri(Weise).(Ⅱ) Male genitalia,parameres,1/3 from inner side before apex of paramere of M.hauseri(Weise) situating an angular process,but the paramere of the new species devoid of these process.Sipho,siplional apex of M.hauseri(Weise) with sharp terminal,but siphonal apex of the new species bifurcate.