The hollow universal joint is one of the vulnerable components in hollow screw coring drill tools， directly affecting their service life. Based on the traditional solid flexible shaft universal joint， a hollow design was implemented. Finite element software was employed to conduct mechanical analysis of the hollow universal joint， investigating the influences of mechanical and geometric parameters on its mechanical performance. Results showed that compared to conventional flexible shaft universal joints， the hollow universal joint with grouting holes exhibited higher stress and strain at the grouting hole locations， making them prone to damage and failure. The stress distribution in other regions remained consistent with hollow universal joints of the same dimensions without grouting holes， indicating that grouting holes did not alter stress conditions in non-hole areas. Stress demonstrated a proportional relationship with torque， while strain increased with torque but exhibited a diminishing growth rate as torque rose， following a nonlinear pattern. When the grouting hole was positioned 250 mm from the end face， both stress and strain reached minimum values， identifying this configuration as the optimal design. These findings establish a foundation for subsequent development of high-performance hollow universal joints.