Tumor recurrence after surgery is the main cause of treatment failure. However, the initial stage of recurrence is not easy to detect, and it is difficult to cure in the late stage. In order to improve the life quality of postoperative patients, an efficient synergistic immunotherapy was developed to achieve early diagnosis and treatment of post-surgical tumor recurrence, simultaneously. In this paper, two kinds of theranostic agents based on gold nanorods (AuNRs) platform were prepared. AuNRs and quantum dots (QDs) in one agent was used for the detection of carcinoembryonic antigen (CEA), using fluorescence resonance energy transfer (FRET) technology to indicate the occurrence of in situ recurrence, while AuNRs in the other agent was used for photothermal therapy (PTT), together with anti-PDL1 mediated immunotherapy to alleviate the process of tumor metastasis. A series of assays indicated that this synergistic immunotherapy could induce tumor cell death and the increased generation of CD3+/CD4+ T-lymphocytes and CD3+/CD8+ T-lymphocytes. Besides, more immune factors (IL-2, IL-6, and IFN-γ) produced by synergistic immunotherapy were secreted than mono-immunotherapy. This cooperative immunotherapy strategy could be utilized for diagnosis and treatment of postoperative tumor recurrence at the same time, providing a new perspective for basic and clinical research.