Prostate cancer (PCa) is one of the most common malignancies in men worldwide, and metastatic castrate-resistant prostate cancer (mCRPC) has shown a poor prognosis. Although chemotherapy and androgen deprivation therapy (ADT) have improved clinical outcomes, the median survival (MS) of patients with mCRPC is still less than 2 years. With the development of poly adenosine diphosphate-ribose polymerase inhibitor (PARPi), the treatment strategy for patients with mCRPC has markedly evolved. Olaparib, a type of PARPi that can selectively induce synthetic lethality in cancer cells with homologous recombination (HR) deficiencies, was the first type of PARPi approved for treating patients with mCRPC harboring mutations in HR repair (HRR) genes. This review discusses and summarizes the latest progress on therapeutic mechanisms, monotherapy, combination therapy, and adverse events of Olaparib.