High power diode laser bars require thermal management packages with high cooling efficiencies and long-term stability. At a constant size, the power output of the diode laser is being increased rapidly; therefore, an efficient heat removal strategy has become even more important. High efficiency microchannel heat sinks are usually used to remove heat from the system. In this study, the fluid flow and heat transfer of an existing diode laser micro-channel heat sink is numerically simulated. To reduce the maximum temperature and obtain a uniform temperature distribution across the diode laser, which leads to extended lifetimes, the simulations are repeated for three different channel geometries. The hydrodynamic and thermal behavior of the heat sinks are then compared. The results show that among all geometries, the sinusoidal structure provides the best thermal performance. Although the system pressure drop increases by 18%, this configuration increases the diode lifetime by 44%.