The present work has attempted to investigate the dependence of Cu infiltration kinetics on in-situ structure modification of W powder skeleton in W-Cu system. In-situ structure modification of W skeleton by addition of 0.3wt%Ni-P eutectic alloy was designed to proceed during heat-up of the W compact for Cu infiltration process. It was found that the Ni-P added W skeleton underwent remarkable stucture change only during heating-up. its structure was composed of large necks of W particles above 0.5 in the ratio of neck to particle size and smooth pore channels. The infiltration experiment showed that the infiltration kinetics for the W-Ni-P followed well the linear relationship of h vs. $t^{1/2}$ the rate constant K of which was in good agreement with the theoretical value. On the other hand, in case of the pure W skeleton a lower K value by 20% than the theoretical one was obatined. Such discrepancy is discussed in terms of skeleton structure induced infiltration mechanics.