The utility model discloses a supporting of roller chain for self -elevating drilling unit cantilever beam, including bearing the support, bear the inside along vertically reaching the chamber that separates that transversely divide into four same size of support, every installs three pneumatic cylinder in separating the chamber, is called a set of pneumatic cylinder, every separates the chamber bottom and is provided with a plurality of dogs along the horizontal even interval in vertical both sides, has a cambered surface backing plate in every common supporting of up end that separates all dogs in chamber, and every cambered surface backing plate upper surface is spread there is the flexible support pad, and every flexible support stacks up the surface and has placed a roller chain support, vertically installs a set of roller chain in every roller chain support. The utility model discloses a device, simple structure, the bearing capacity is big, the maintenance of being convenient for.