In this work, a PEGylated porous molybdenum disulfide nanoflower (MSP) with abundant defects was facilely synthesized for tumor-targeted chemo/photothermal theranostics. Furthermore, a reduction-coordination induced selective degradation of MSP in tumor was first proposed, which could promote redox dyshomeostasis via GSH depletion for ROS-accumulated chemodynamic therapy. Meanwhile, this biodegradation of MSP regulated a sustained H₂S release within tumor and achieved a controllable H₂S gas therapy via enhancing the glycolysis to acidify the tumor cells (glycolysis disorder). Synergistically, these performances were further enhanced via NIR photothermal heating, where excellent therapeutic outcomes with good biosafety were accomplished in vitro and in vivo. These characteristics, together with the unique biodegradation and no obvious side-effects of the nanoparticles, suggested a potential therapeutic strategy for precise tumor treatments.