Disclosed in the present invention is the use of a recombinant Ganoderma lucidum immunomodulatory protein (rLZ-8) in the preparation of a medicine for resisting melanomas. The present invention uses in situ tumour and metastatic tumour experimental animal models to study the anti-tumour effect of rLZ-8, which have indicated that rLZ-8 can significantly inhibit melanoma in situ tumour growth and metastasis lesion formation.