Abstract: By incorporating conductive fillers into the polyurethane matrix, a novel substrate-free, stretchable, and highly flexible electric heating film was developed. Its structural characteristics, thermal stability, mechanical properties, and aging performance were investigated. The results showed that the porous structure of the matrix and the uniformly distributed conductive fillers formed a stable conductive network, significantly enhancing the conductivity and mechanical performance, while also exhibiting good thermal stability. When the conductive filler content was 10 wt%, the electric heating film achieved a balance between conductivity and mechanical properties, demonstrating excellent thermal response characteristics. Both electrical degradation and UV aging led to performance degradation of the electric heating film. The innovative design in this study of a highly stretchable and flexible electric heating film provides a new approach for the development of electric heating products.