Abstract: The surface free energy, color diffusion and polarity power of the modified wood were calculated by means of the YoungGoodGirifalcoFowkes expression after the wood surface was treated by N2 and O2 cold plasma, and the contacting angles were tested with water and diiodomethane after having been placed for different time durations. The results showed that the surface free energy of the modified wood that was treated by N2, O2 cold plasma increased prominently, whose value was increased by 54.23% and 54.41% respectively after being treated for 1h. But the surface free energy of the modified wood decreased gradually with the time going on, whose value declined prominently within 6d-10d, and almost returned to the control in 14d-21d. The result also showed that contacting angles of the modified wood treated by O2 cold plasma were smaller than that of treated by N2 cold plasma, indicating the effect was better.