Porous PDMS with excellent properties, is widely used in flexible electronic devices. However, the heat generated during operation, combined with the porous structure, can affect the substrate’s thermal conductivity, which may impact functionality. This work develops a finite element model to investigate the thermomechanical response of flexible electronic components on periodic porous PDMS substrates under thermal pulse loads. The analysis compares temperature, thermal stress, and displacement variations in the central unit of the functional layer at different load magnitudes, evaluating the differences between the substrate and functional layers. Results show that as the thermal pulse load increases from n = 1 to n = 3, temperature, thermal stress, and displacement in the functional layer’s central unit increase by 0.51%, 200.03%, and 192.38%, respectively. The substrate experiences significantly higher thermal stress and displacement, indicating that the porous structure disperses external impact energy, protecting the functional layer. These findings provide essential data for optimizing the design and durability of flexible electronic devices.