The Gansu leaf warbler (Phylloscopus kansuensis) is a small passerine bird known only from China. It belongs to the leaf warbler genus Phylloscopus within the family Phylloscopidae. It was formerly treated as a subspecies of Pallas's warbler (P. proregulus) but is now regarded as a separate species based on differences in voice and cytochrome-b gene sequences.It is 10 cm long, slightly larger than Pallas's warbler. It has greenish upperparts, pale underparts and a pale rump.