provided is a double - chain sirna molecule targeting a microphthalmia - associated transcription factor mitf coding gene . a sense strand of the sirna molecule has a sequence of seq id no : 3 and an anti - sense strand has a sequence of seq id no : 4 , and the anti - sense strand specifically binds to mrna of the mitf coding gene , to degrade the mrna , thereby reducing the systhesis of melanin . further provided is an application of the sirna molecule in freckle whitening cosmetics or the preparation of medicines for treatment of diseases related to melanin gene .