Description and illustrations of a new species of the genus Simulium Latreille collected from Mount Tai,Shandong Province,China on adult,larval and pupal stages.All the specimens are kept in the Medical Entomology Collection Gallery,Academy of Military Medical Sciences,Beijing.The new species is assigned to the subgenus Eusimulium and closely related to Simulium (Eusimulium) satsumense Takaoka,1976,S.(E.)kuandianensis Chen et Cao,1983,S.(E.)weiningense Chen et Zhang,1997,but it is easily distinguished from three species mentioned above by the shape of genital fork of female,ventral plate,median sclerite of male,larval head spots,cleft and pupal setae and spines of terga and sterna.Holotype ♀,paratype 1,2pupae,7 mature larvae,from Changshou Bridge (500m) (36.3N,117.1E),Mount Tai,Shandong Province,China 23 June,1999.