The present disclosure relates to a method for wafer level packaging and a package structure thereof. The method includes several steps. A through hole is formed in the interposer with a thickness that is less than the length of a first conducting pillar. The first conducting pillar is disposed inside the through hole. A redistribution layer is disposed and electrically connected with the first conducting pillar. A solder ball is disposed on the redistribution layer so as to form a wafer level packaging structure.