Loop heat pipe (LHP), which is the star-rated way to solve high heat flux heat transfer, is a promising heat dissipation technology for electronic devices. The optimized design of porous wick in LHP has become the key to increasing the heat transfer capacity and reducing costs. In this study, a polymer material-polyethersulfone (PES) film was chosen as the porous wick. Theoretically, the PES wick has a special structure with dual pore size, which achieves a synergistic enhancement of capillary force and permeability. The experimental investigation compared the heat transfer capacity of LHP with the PES wick, copper mesh wick, and sintered nickel powder wick. The PES wick shows a most significant performance than the other two wicks. The heating surface temperature remains 62 degrees C in a 55% filling ratio when the LHP is under 300 W heat load. The LHP system and evaporator have respectively the thermal resistance of 0.161 degrees C/W and 0.056 degrees C/W. In addition, PES wick shows great potential for application in the LHP field with the advantages of light weight, simple preparation, and low cost. This paper sheds some light on the LHP wick choice to enhance heat transfer.