Surattha diffusilinea is a moth in the Crambidae family. It was described by Hampson in 1919. It is found in Australia, where it has been recorded from New South Wales. The forewings are white, faintly tinged with rufous and slightly irrorated with blackish. There is a black antemedial line and two similar medial lines. The hindwings are white, faintly tinged with rufous.