Elysia trisinuata is a species of sea slug, a marine gastropod mollusc in the family Plakobranchidae.

Elysia trisinuata is pale green with minute orange spots.

The colour is provided by the chloroplasts which are found in fine ducts in the body wall.

[2] Elysia trisinuata is found in the eastern Pacific Ocean off the coasts of Japan, southern China, Hong Kong and the Hainan Islands.

It occurs in shallow waters and the intertidal zone where it feeds on algae including Codium arabicum.