This study presents a novel approach to reconstructing density fields from shadowgraph images using a physics-informed framework. By integrating traditional shadowgraph imaging techniques with physics-informed neural networks (PINNs), we effectively capture refractive index variations within complex flow fields. The proposed method addresses the inherent challenges of shadowgraphy, such as noise and limited spatial resolution, enabling accurate visualization of fluid dynamics. Experimental results demonstrate the feasibility and robustness of our approach, with significant agreement observed between the reconstructed density fields and experimental measurements. This research contributes to the advancement of non-intrusive diagnostic techniques in fluid mechanics and enhances our understanding of flow structures in various applications.