SCR driving will give the rig's electric system a larger harmonic pollution, causing the system power quality deterioration, electrical equipment overheating, shortened life expectancy, loss increasing, and electromagnetic interference on communication facility. Therefore, we must take effective measures to suppress harmonic pollution. Aiming at the problem of the harmonic produced by the oil rig's SCR electric drive system, the distribution of the harmonic source on the 600V bus and induced voltage wave distortion, put forward two schemes that each of the SCR electric drive system equipped with a APF device and additional reactor, combining these two schemes to achieve a better harmonic suppression purpose. The experimental results show that this method can greatly restrain harmonic produced by the SCR system and improve the drilling power quality. It has a very important engineering application prospect.