Several tree-shaped microchannel networks with/without loops are numerically examined and compared for application in cooling of electronic components. The physical model of microchannel electronic cooling system is set up with tree-shaped networks. The tree-shaped microchannel nets are embedded in a disk-shaped heat sink, which is attached to a chip to remove the heat dissipated by a chip. The effects of total branching level and loops on the thermal and flow performances of heat sink system are investigated numerically. Results show that tree-shaped nets with loops provide a great advantage when the structure experiences accidental damage to one or more channel segments since the loop assures continuity of coolant flow. Under blockage of some branches, the channel networks only experience an increase of pressure drop while maintaining the capability to remove the heat generated by the chip.