Complex system analysis is of great significance in the precision engineering of polymer processing. The compositions of thermal regulation units and multiple devices pose challenges for inner-mold analysis and increase investment in sensing technology in injection molding. This study proposes a mold–product thermally regulated integration (MPTI) methodology for the first time to establish a full-scale prototype and achieve accurate polymer flow, energy transfer, and product-forming state identification in injection molding. The numerical analysis results were compared with the experimental data and verified. The filling duration and pressure drop at the velocity/pressure switchover position were measured at injection velocities of 100–150 mm·s−1. The thermal effects of heat conduction at the inner surface of the mold and the viscous dissipation of the molten resin were experimentally validated by adjusting the hot-runner system and cooling unit. The accuracies of MPTI for the filling duration, pressure variation, and temperature detection were 7.7 %, 9.9 %, and 4.1 %, respectively. The final product deformations in MPTI were 7.8 % and 3.7 % smaller in the x and z directions, respectively. Our method merges polymer flow-state identification, energy transfer analysis, and product quality verification, with the potential for modeling complex thermal molds in manufacturing applications.