The solid surface free energy components of ε-CL-20 were determined by the Washburn equation with the thin-layer wicking technique. The results show that the surface free energy components of ε-CL-20 from different liquids are in good agreement with each other. The total surface free energy r^T_s of ε-CL-20 is 42.65 mJ·m^-2, which accords with the theoretic calculation result 41.28 mJ·m^-2. The other determined values are dispersive component r^LW_s=40.61 mJ·m^-2, polar component r^AB_s =2.042 mJ·m^-2, electron acceptor component r＋s =0.32 mJ·m^-2 and electron donor component r^-_s=13.02 mJ·m^-2. The results also show that the apolar component is the main part in the surface free energy and ε-CL-20 is a bipolar solid, which is more basic than acid.