Abstract: This study conducts static push-out tests on three groups of steel-C80 high-strength concrete stud connectors with six different stud length-to-diameter ratios (1.2, 2.3, and 3.8). The experimental results indicate that: as the l/d increases, the failure modes of the stud connectors transition sequentially from stud pullout failure to a mixed failure of stud shear at the root and concrete pullout, and finally to stud shear fractured; and even when the l/d is less than 4, the studs can still achieve shear fractured, ensuring the full development of shear capacity. Based on the three failure modes observed in the push-out tests and drawing from the concrete punching shear failure theory, a shear force analysis model for stud connectors subjected to stud pullout failure was developed. A calculation formula for the minimum length-to-diameter ratio of studs based on the stud shear fractured mode was proposed and validated through comparison with relevant literatures. Using the ABAQUS program, a finite element analysis model of stud connectors was established. Parametric analyses of different concrete strengths indicate that: in steel–high-strength concrete composite structures, even when the l/d is less than 4, if it meets the proposed minimum length-to-diameter ratio formula, the stud shear fractured mode can still be achieved, ensuring the full utilization of stud load-bearing capacity, making it suitable for practical engineering applications.