A method of inhibiting the flow boiling instability in microchannel with the hydrodynamic cavitation effect was promoted and it was proved by experiment as well. According to experimental results, cavitation structure at the entrance of microchannel benefits to the stability of flow boiling with great range of heating input. Based on this result, a microchannel phase change heat sink with single bar by using of the hydrodynamic cavitation effect was developed, and its thermal parameters, electric-optical parameters and maximum heat dissipation potential were also tested. According to the experimental data, when the output power was about 70 W, the photoelectric efficiency achieved the maximum value, and the largest heat dissipation capacity of the heat sink exceeded 100 W whose heat flux density was 870 W/cm2.