Version 2 (2026-06-06): This version supplements the complete derivation process of the Qi medium model, corrects some symbol definitions, and adds key mathematical steps to enhance the traceability and reproducibility of the theory. The numerical calculation of the gravitational light deflection angle of the Crab Nebula pulsar is also refined. The scientific value and theoretical rationality of general relativity are unquestionable, and its predictions of gravitational optical and celestial mechanical effects have been verified by numerous astronomical observations. However, physical theories are not the ultimate truth of the universe; multiple logically self-consistent theoretical interpretations can coexist for the same astronomical phenomenon. This work abandons the geometric interpretation of spacetime curvature. Based on the cosmic fluid framework of the Qi medium, which assumes cosmic space is filled with a uniform continuous medium with fundamental fluid properties, we establish the coupling relation between radial density distribution and refractive index of a spherically symmetric Qi medium. Model parameters are calibrated independently using the perihelion precession data of Mercury. The gravitational light deflection angle of the Crab Nebula pulsar is calculated quantitatively. The results show that the deflection angle predicted by the Qi medium model is 0.319", which falls exactly within the measured range of 0.31"-0.33" and agrees well with the prediction of general relativity. This work does not contradict general relativity but provides an equivalent theoretical framework from a new medium perspective. It confirms that gravitational optical phenomena can be explained reasonably by different physical mechanisms and offers new thoughts and quantitative support for diversified interpretations of gravitational effects. Keywords: Qi medium model; gravitational optics; light deflection; Mercury precession; diversified theoretical interpretation