The larval and imaginal stages of Baetis maculosus sp. nov., a new species of Baetidae from China, are described and illustrated. The spotted color pattern of the new species resembles Baetis taiwanensis (Müller-Liebenau), but can be readily distinguished from it and other members of the genus Baetis by the following diagnostic characters: inner margin of right mandibular incisors of the larvae lacks a row of fine, short setae; tibiae dorsally with minute and sharp main setae; and 6 pairs of gills on abdominal segments 2–7. The hind wing of the imago has a crossvein between the costa and the longitudinal veins proximal to its bifurcation; segments II of the genital forceps have concave interior surfaces near their base, and the apical portion is densely wrinkled.