In the presented study, a novel micro cooling system for electronic devices using a micro capillary groove evaporator was proposed. Based on experimental data in open(atmospheric) condition, we found that liquid level has an obvious influence on evaporating heat flux. For a given liquid level, there exists an optimum groove size, which maximizes evaporation heat transfer capacity. By using the optimum groove sizes in the open condition, two types of closed cooling sytems for CPU chips for personal computers were designed: one was for desktop models and the other for notebook models. Their cooling performance to keep CUP chip temperature belos 90℃ reached 3.35×105W/m2 and 2.51×105W/m2,respectively, for the desktop model by using ethanol and the notebook model by using methanol. Experimental results show that the maximum cooling capacities strongly depend on the condensation capacities of condensers in the closed cooling systems and volume fractions of working liquid in the evaporators.