MicroChannel heat sink is a promising cooling technology for semiconductor devices with a high cooling capacity and low mass flow rate requirement. Nowadays, semiconductor devices are widely used in industry and improved in size and clock speed which leads to higher heat flux. In this paper, three kinds of microchannel heat sink designs are proposed and the cooling performance is investigated by CFD. Uniform heating condition is applied to the swirl microchannel heat sink. The non-uniform heating condition is divided into local high heat flux and continuously varying heat flux to simulate the electrical devices and concentrated photovoltaic cell, respectively. The cross-linked microchannel heat sink and hybrid micro heat sink are used to remove the local high heat flux. Two different sizes and numbers of hotspots are designed and applied to these two heat sinks. The straight microchannel heat sink is designed for continuously varying heat flux. Water is used as coolant and copper / silicon is selected as heat sink material. The heat flux varies from 10 W/cm2 to 100 W/cm'. The inlet velocity varies from 0.5 m/s to 1 m/s. The maximum temperature, temperature gradient, pressure drop and total thermal resistance are chosen to be criterion of evaluating their cooling performance.