Abstract: Through-silicon-vias (TSVs) has been identified as one of the most significant devices in 3D-integration. This paper addresses the comparative studies of two types of TSVs, i.e. copper-based TSVs (Cu-TSV) and low resistivity silicon pillar based TSVs (LRS-TSV), focusing on impact of geometric dimensions on their thermal-mechanical reliabilities. During the studies, finite element analysis (FEA) were utilized. First, based on the experimental dimension of the two kinds of TSV, the maximal protrusion height and thermal stress were simulated and compared under 350℃. Second, by changing the factors of experimental model such as TSV diameter, height and pitch, the difference of their thermal mechanical characteristics was investigated and compared. The results show that the LRS-TSV performs better in terms of thermal mechanical properties.