Diachrysia stenochrysis is a species of moth of the family Noctuidae.

It is found in Europe, the Caucasus, the Far East, Primorye, Ussuri, Korea, Manchuria, Mongolia, Transbaikalia, Siberia and Japan.

Warren (1914) states (original description) P. stenochrysis spec.

As large as or larger than Diachrysia chrysitis, but with the forewing narrower;the costal portion of median fascia with conversely oblique edges, and nearly twice as wide on costa as in Diachrysia nadeja Oberthür, 1880.

The larvae feed on Urtica species and other plants.