A new genus with a new species, Exilibittacus lii n. gen., n. sp., and a new species, Megabittacus spatiosus n. sp., are described and illustrated. Both of them belong to the family Bittacidae (Mecoptera). These specimens were collected respectively from the Middle Jurassic of Jiulongshan Formation at Daohugou in Inner Mongolia and from the Late Jurassic to Early Cretaceous of Yixian Formation at Dawangzhangzi in Liaoning, China. In Exilibittacus n. gen., both RP MA and MP have four branches in forewings, while both have three branches in hind wings, and RP1 2 and MP3 are not forked. This is the first time that the character ‘MP with three branches in hind wings’ is reported for the Bittacidae. Based on data on Megabittacus spatiosus n. sp., the diagnosis of Megabittacus is revised and a key to the known species is provided. Morphological changes in hangingflies from Middle Jurassic to present are discussed based on body length, wing length, and forewing/body length ratio.