Sinojassus gen. nov. of tribe Iassini is described based on: two new species from China, S. loberus Dai, Zhang & Zhang sp. nov. (type species), S. aspinus Dai, Zhang & Zhang sp. nov.; one new species from China and Thailand, S. compressus Dai, Zhang & Zhang sp. nov.; and one new species from Vietnam, S. webbi Dai & Dietrich sp. nov. Detailed morphological descriptions, illustrations and a key to species are provided. The new genus resembles Coriojassus Evans, Hyalojassus Evans and Trocnadella Singh-Pruthi in the structure of the male genitalia. The style has an elongate apodeme and short apophysis, the connective is absent, and the aedeagus is simple, without processes, and connected to other parts of the genitalia by membranous ligaments. A key to Oriental genera of Iassini is also provided.