Multifunctional nanotheranostic agent with high performance for tumor site-specific generation of singlet oxygen (O) as well as imaging-guidance is crucial to laser-mediated photodynamic therapy. Here, we introduced a versatile strategy to design a smart nanoplatform using phase change material (PCM) to encapsulate photosensitizer (zinc phthalocyanine, ZnPc) in copper sulfide loaded Fe-doped tantalum oxide (Fe-mTaO@CuS) nanoparticles. When irradiated by 808 nm laser, the PCM is melted due to the hyperthermia effect from CuS nanoparticles, inducing the release of ZnPc to produce toxic O triggered by 650 nm light with very low power density (5 mW/cm). Then, the produced heat and toxic O can kill tumor cells in vitro and in vivo effectively. Furthermore, the special properties of Fe-mTaO endow the nanoplatform with excellent computed tomography (CT) and T-weighted magnetic resonance imaging (T-MRI) performance for guiding and real-time monitoring of therapeutic effect. This work presents a feasible way to design smart nanoplatform for controllable generation of heat and O, achieving CT/T-MRI dual-modal imaging-guided phototherapy.