An immunosuppressive agent having the structure of formula (I), a preparation method therefor, and pharmaceutical use thereof. A series of the compounds have strong inhibitory activity on PD-1/PD-L1 interaction, can be widely used for preparing medicaments for preventing and/or treating cancers or tumors, immune-related diseases and disorders, communicable diseases, infectious diseases or metabolic diseases mediated by PD-1/PD-L1 signaling pathway, and is expected to be developed into a new generation of PD-1/PD-L1 inhibitors.本發明涉及一種式(Ⅰ)結構免疫抑制劑及其製備方法和在藥學上的應用。本發明系列化合物具有對PD-1/PD-L1相互作用有很強的抑制活性，可廣泛應用於製備預防和/或治療由PD-1/PD-L1訊號途徑媒介的癌症或腫瘤、免疫相關疾病及失調、傳染性疾病、感染性疾病或代謝性疾病的藥物，有望開發成新一代PD-1/PD-L1抑制劑。
