De novo malignant tumour will be one of the first dead reason of the long term survival transplantation patients. The depression of immune system of the transplanted recipients and abnormality of internal environment due to the acception of therapy of the immunosuppressive agents, which resulting in the tumorigenesis. The immunity reaction is contradict between the transplantation and cancer in post transplant condition. This topic has been paid close attention recently. Pioneer studies show that myeloid derived suppressor cell (MDSC) accumulated in the allografts of tolerant recipients and tissue of tumor, in where MDSC induced dendritic cells to be the tolerogenic dendritic cells. It is unknow about the mechanism of action. In this review, we try to summarize some aspects of the study progression and the role of MDSC in post transplant cancer.