This thesis focuses on the interplay between liquid crystal and polymer layers, exploring the dielectric properties of the polymer/liquid-crystal composite system. We adopt the phase-separated composite film (PSCOF) technique to simplify the complicated system, the result is a stratified polymer/liquid crystal composite film. This study exploits the dielectric spectroscopy to analyze various polarization behaviors under different environmental temperatures and photo-polymerization states. To investigate the interface polarization being specifically exhibited in the composite system, the concept of concentration polarization layer has been introduced to describe the charge-cumulative behaviors at the interface. The relaxation frequency of the interface polarization sheds light on the structure of the composites with two components of given dielectric constants, which enables one to roughly calculate the thickness of the liquid-crystal layer in PSCOF without destroying the cell, which could be further developed as a technique of non-destructive in-situ thickness measurement in a phase-separated composite.