The integration of automotive electronics puts extreme demands on the miniaturization, high-density and extreme working condition reliability of automotive smart connectors. Polybutylene terephthalate has become the core shell material by virtue of its excellent electrical insulation, heat resistance and dimensional stability, but the multi-field coupling of melt flow, heat conduction, pressure transfer and crystallization shrinkage in the injection molding process is prone to inducing non-uniform crystalline orientation and residual stress concentration. Especially in the manufacture of microstructured connectors, the above coupling effect is significantly exacerbated, resulting in defects such as header warpage, terminal coplanarity misalignment, and other defects, which directly threaten the reliability of the on-board electronic system. The existing process optimization lacks the knowledge of systematic coupling mechanism, therefore, this study focuses on the multi-field dynamic coupling mechanism of the injection molding process of PBT-based connectors, and explores the temperature-flow-stress interaction law in depth, with a view to providing a theoretical cornerstone for the manufacturing of high-precision and high-reliability in-vehicle electronic devices.