A method for manufacturing an extract of Zingiber zerumbet, which is used to manufacture the extract of Zingiber zerumbet for diabetic retinopathy, includes: soaking a raw sample of Zingiber zerumbet with vinegar for 8 hours boiling the soaked product at 1.5-2.5 kg/m2, 95-105° C. for 30 minutes to obtain a processed sample of Zingiber zerumbet and extracting the processed sample of Zingiber zerumbet with an extractant being water or 95% ethanol at 70-90° C. for 8 hours to obtain the extract of Zingiber zerumbet. The present invention further relates to the extract of Zingiber zerumbet and a method for diabetic retinopathy by administrating the extract of Zingiber zerumbet to a subject in need.
