Herein, a multifunctional biomimetic nanocarrier (siRNA‐CaP@PD1‐NVs) is developed, which can not only enhance the cytotoxic activity of immune cells by blocking PD1/PDL1 axis, but also reduce tumor immune escape via Pbrm1/PDL1 gene silencing, leading to a significant improvement in tumor immunosuppressive microenvironment. Here, CD274 is linked to neoplasm.