In the present work, experimental trials were carried out to investigate the influence of packing density on performance of porous wick for loop heat pipe (LHP). Carbonyl nickel powders with an average size of 1.19 mu m were used as raw materials. During the filling of powders the graphite mold was put on a mechanical vibrator for different times to get different packing densities. The results show that the porosity, average pore size and permeability decrease with the increasing packing density, respectively. However, the capillary pressure increases with it. And there are no obvious effects on micro-structure and shrinkage ratio. Moreover, the packing density has complex effects on thermal property. After the optimization of parameters, the cylindrical wick with porosity of 59%, average pore size of 1.41 mu m, permeability of 1.25 x 10(-13) m(2), capillary pressure of 204 kPa and excellent thermal property could be realized. (C) 2014 Elsevier B.V. All rights reserved.