Vein deposits, important carriers of metal sulfides, typically exhibit low resistivity. Transient Electromagnetic (TEM) methods have been widely employed for detecting such low-resistivity deposits, with forward modeling forming the basis of field data acquisition design and subsequent data processing and interpretation. To optimize field exploration strategies and facilitate effective data interpretation, this study constructs a series of low-resistivity vein deposit models buried beneath conductive cover layers. We use a 3D vector finite element forward modeling approach to systematically investigate the effects of transmitter loop scale, cover layer conductivity and thickness, as well as deposit conductivity, thickness, and dip angle on the resolution of TEM methods. The results show that increasing the transmitter loop scale enhances the total induced Electromotive Force (EMF) field but reduces the ratio of the total field to the background field, indicating a decrease in resolution. Using the constructed model as an example, increasing the transmitter loop scale by a factor of three leads to a 7/9 reduction in resolution. An increase in the conductivity and thickness of the cover layer significantly weakens the detection capability of TEM. Similarly, a decrease in the conductivity and thickness of vein deposits results in reduced detection capability. For instance, with a 300 m transmitter loop, increasing the cover layer conductivity by a factor of 10 leads to a 94.5% reduction in resolution, while increasing the cover layer thickness by 2.5 times reduces the resolution by 96.7%. Reducing the deposit conductivity by 49/50 lowers the resolution by 98.8%, and reducing the deposit thickness by 9/10 lowers the resolution by 96.7%. Changes in the dip angle of the deposit also affect the location of the measurement point with the strongest resolution. For example, at a 25° dip angle, the measurement point above the center of the deposit exhibits the strongest resolution, whereas at a 75° dip angle, the strongest resolution shifts to the measurement point above the deeper end of the deposit. This study shows that the physical properties of the cover layer and vein deposits significantly impact the detection capability of TEM, with these effects being more pronounced when using small-scale transmitter loops. Therefore, exploration design must strike a balance among transmitter loop scale, resolution, target dimensions, and operational efficiency.