Abstract: The C-axis system of the C-arm Digital Subtraction Angiography （DSA） device plays a pivotal role in medical image acquisition, making its strength and stiffness vital in the design of C-arm machines. Utilizing finite element analysis through ANSYS, we investigated the stress distribution and deformation of the C-arm component under four extreme working conditions: vertical, parallel, and ±45° elevation angles. This analysis enabled us to verify the strength and stiffness of the C-arm component, thus confirming the overall reliability of the structure. To address the challenge of insufficient contact between the guide rails at the connection mechanism of the C-axis system, we optimized the layout of the guide rail components. Subsequently, we conducted simulation verification on the modified guide rail surface contact strength, achieving a 20.88% reduction in maximum surface contact stress.