Numerical simulations were carried out to investigate the thermal-hydraulic characteristics of water flowing through different heat sinks. Calculations show that the internal fin structure of the heat sink has an important influence on the flow resistance and heat transfer. The zigzag channel has the largest flow resistance, while the straight channel has the smallest flow resistance, but the heat transfer capacity is opposite. In addition, the performance of heat sinks when inserting pin fins with different shapes in straight channels was also compared. The results show that the thermal resistance of circular pin fins is the smallest.