This is a single-arm, open, single-center clinical study to evaluate the efficacy and safety of RC48-ADC in patients with mCRPC who have progressed after NHT. A total of 40 patients with mCRPC with immunohistochemically confirmed HER2 expression who had progressed after treatment with at least one novel endocrine therapy will be included in this study. Participants will receive RC48-ADC intravenous injection (2.0 mg/kg, Q2W) until disease progression or death. During the treatment, participants will evaluate every 4 weeks, including PSA testing every 4 weeks and tumor evaluation according to PCWG3 standards every 8 weeks. If the patient develops disease progression, the treatment will be discontinued and survival follow-up will be conducted every 8 weeks.