Mechanical Rubbing still is an useful alignment method in this time. In this study, we investigated the surface wettability of rubbed polyimide(PI) thin film. By using contact angle measurements, we found the surface free energy have strong connection with surface roughness in different rubbing times. We also discussed the wettability of rubbed PI thin film in parallel and anti-parallel of rubbing direction. We found that if we rubbed PI thin film 3 times in 0.3mm depth then the structure of SSFLC is more uniform than the alignment effect of other rubbing times and we found that the values of polar energy in parallel and anti-parallel of rubbing direction are very close. In the other part of study, we degenerated the polyimide before coating. We found that the reflection anisotropic spectrum(RAS) have a blueshift and the rubbing strength will be more influential in the wettability of PI thin film than the film with no degenerate process.