For dissipating the increasing heat in high flux microelectronic device, an original microchannel heat sink with staggered triangular ribs induced vortex flow is designed. In this work, the width (Wch) and height (Hch) of a single microchannel with staggered triangular ribs (MC-STR) are both 0.2 mm, as well as the width (Wr), height (Hr) and length (Lr) of the triangular rib are in ranges of 0.025–0.15 mm, 0.012–0.072 mm and 0.06–0.16 mm, respectively. The influences of the relative rib width (Wr/Wch), relative rib height (Hr/Wch) and relative rib length (Lr/Wch) on the hydrothermal behavior and entropy generation in MC-STR are numerically analyzed at the Reynolds number (Re) of 243–639. The results show that the increases in Wr/Wch and Hr/Wch can effectively improves the thermal performance, and reduce augmentation entropy generation number, but increase the flow resistance. In addition, the rise of Lr/Wch has weak effect on hydrothermal behavior and entropy generation. Overall, the MC-STR with Wr/Wch = 0.5, Hr/Wch = 0.3 and Lr/Wch = 0.5 at Re = 639 yields the highest performance evaluation criterion (1.502). Moreover, the minimum augmentation entropy generation number (0.236) is achieved at MC-STR with Wr/Wch = 0.5, Hr/Wch = 0.36 and Lr/Wch = 0.4 as Re = 639.