Abstract: Prostate cancer is the most common malignant tumor of male reproductive system, which seriously threatens men's health. It has been shown that the existence of zinc ions can inhibit the growth of prostate cancer cells. In addition, photothermal treatment of cancer is attracting more and more attention due to its high accuracy and efficiency. In this study, zinc ions loaded black phosphorus nanosheets (BP-Zn) were prepared, and the photothermal therapy efficiency of the system on human prostate cancer cells (PC-3) was evaluated. The inhibition effect of zinc ions on PC-3 cells was studied. It was demonstrated that the toxicity of zinc ions on PC-3 cells was concentration- and time-dependent. Moreover, it can be seen from in vitro photothermal therapy that the treatment effect of black phosphorus assisted by zinc ions is superior to that of black phosphorus alone. This study further studied the in vivo therapeutic effect of BP-Zn. The results once again confirmed that the combinational photothermal treatment of zinc ions and BP had excellent anti-tumor effect. The animal procedures were approved by the Animal Ethics Committee of Tsinghua Shenzhen International Graduate School.