Four different polyimides were synthesized to examine surface properties according to chemical structure. Contact angles were measured on polyimide films by using quantitative imaging sytstem. Dispersion(D), polar(P), hydrogen-bonding(H) liquids were used. Critical surface tensions of films were estimated by Zisman plot, Young-Dupre-Good-Girifalco plot, log(1+cosθ) versus log(γI) plot. The estimated values of four different polyimide films by Zisman plot are smaller than that calculated by the plot of 1+cosθ vs. 1/γL0.5 or the plot of log (1+cosθ) vs. logγL. On the Zisman plot, the relationship between cosθ and VL shows a straight line when the value of γL is in the vicinity of γC. Because γL has a much larger value than γC. a downwardly convex curve is shown in case of hydrogen-bonding liquids. Experimental data are well fitted with a downwardly convex curve. Solid surface tension(γs) of four different polyimide films were determined by using geometric mean equation. Solid surface tension of polyimides ranges from 35.1 dynes/cm to 43.1 dynes/cm, and increases in the following manner: BPDA-EDA < BPDA-BAPP < BPDA-BAPE.