The Mesozoic mecopteran family Mesopsychidae has attracted extensive attention by their long proboscis that is presumably associated with pollination of early gymnosperms. Three previously reported species of Lichnomesopsyche Ren, Labandeira, and Shih, 2010 from the Middle–Upper Jurassic Haifanggou Formation at Daohugou (Inner Mongolia, northeastern China) display distinct resemblances in wing venation, so that their classification, based on currently described characters, remains elusive. Herein, we describe and figure exquisitely preserved male genital structures of L. gloriae Ren, Labandeira, and Shih, 2010, L. daohugouensis Ren, Labandeira, and Shih, 2010, and L. prochoristaLin et al., 2016, which can be used for defining and recognizing the three species. Our discovery indicates that the male genitalia are the major critical structures for species-level classification of the peculiar genus Lichnomesopsyche. Details of the maxillary palps and legs of L. gloriae and L. daohugouensis are also described.