Hererin, it was confirmed that PEG-ZnPP-SDT could significantly increase ROS production, leading to the collapse of mitochondrial membrane potential in ovarian cancer SKOV3 cells, the leakage of cytochrome c from mitochondria to the cytoplasm, and finally the activation of the mitochondrial–caspase apoptotic pathway. The gene discussed is CYCS; the disease is ovarian cancer.