Graphite as refractory materials has been dried using a vacuum annealing treatment by varying the exposure time for (0, 6, 8, 12, 24 hours) at temperature of 1000 °C. The oxygen to carbon atomic ratio (O/C ratio), assessed using X-ray photoelectron spectroscopy, decreased with increase of temperature and exposure time. Wetting angles between silicon and graphite were measured for silicon droplets. It was found with a low O/C ratio, the statistic contact angle may reach 82 °. In contrast, a high O/C ratio leads in angles around 27°. The infiltration of silicon into the graphite was occurred during the experiments. With increasing of O/C ratio, the infiltration depth of molten silicon increased.