To address the reliance on experience-based puncture guidance and the lack of objective quantification of thermal fields during tumor thermal ablation, a navigation and thermal-field measurement scheme based on multi-source information fusion is presented. Within a unified spatiotemporal reference framework, preoperative multiphysics finite element analysis (FEA), intraoperative augmented reality(AR)-based visual localization, and computed tomography(CT)-based thermometry are integrated to enable visualized puncture guidance and three-dimensional quantitative reconstruction of the ablation temperature field. Multiphysics modeling establishes the relationship between ablation parameters, tissue thermal response, and damage distribution, providing energy-coverage constraints for preoperative needle placement planning. Augmented reality technology supports accurate registration between virtual planning data and the physical surgical space, facilitating intraoperative needle guidance, while calibration between computed tomography values and temperature enables voxel-level temperature inversion from intraoperative imaging for objective thermal-field measurement. Ex vivo porcine liver ablation experiments and abdominal phantom puncture experiments are conducted to verify the navigation and thermal-field measurement framework. Experimental observations indicate that favorable accuracy and stability are achieved in ablation zone prediction, puncture path guidance, and thermal-field reconstruction, with overall performance satisfying clinical safety requirements for tumor thermal ablation. The presented scheme enables a transition from purely geometric navigation toward physically quantitative characterization of ablation thermal fields, providing objective metrological support for planning validation, intraoperative assessment, and decision optimization.