The invention relates to a daphnane diterpenoid resistant to a prostate cancer and a preparation method thereof. A daphnane diterpenoid compound as represented by formula (I) or formula (II) significantly inhibits the proliferation of various prostate cancer cells; the activities of some such compounds at a cellular level and an animal level are higher than that of the existing clinical targeting drug enzalutamide; and the daphnane diterpenoid compounds have strong synergistic effects when used in combination with the enzalutamide and are expected to become candidate drugs for treatment or adjuvant treatment of a castration-resistant prostate cancer.