Thermoelectric cooler (TEC) is attractive for cooling electronic devices because of its light, compact size, quiet and vibration free characteristics. However, its cooling performance is restricted by the thermal resistance at TEC hot side. To improve the TEC cooling performance, a gravity-assisted heat pipe (GAHP) was proposed to attach on the TEC hot side. The cooling feasibility of the TEC system coupled with a GAHP was experimentally investigated in a climatic chamber, compared with a TEC system coupled with an air cooled-heat sink on its hot side. It was observed that the cooling capacity of TEC was improved by 64.8% using GAHP. A mathematical model was established to analyze the effect of refrigerant filling ratio, TEC hot side temperature and air flow rate. Optimal parameters of the proposed system were evaluated from the heat pipe perspective. Findings showed that the optimal refrigerant filling ratio was 134%, which resulted in the maximum heat transfer ability. Increasing air flow rate was able to improve the cooling capacity but with a limitation caused by the restriction of TEC.