The invention discloses an arc-shaped double-blade drill bit of a hole digger. The arc-shaped double-blade drill bit is characterized in that two hole digging blades are respectively an arc-shaped blade with the outer side wider than the inner side, so that the outer edges of the blades are widened, the wear resistance of the blades is greatly improved, and the utilization ratio of the blades is greatly increased; the arc-shaped double-blade drill bit is detachably connected with a seamless steel tube drill stem in a threaded mode, and an earth-cutting helical impeller and the seamless steel tube drill stem can be maintained when the blades are worn and need to be replaced with new ones, so that the loss cost of the drill bit is saved. The arc-shaped double-blade drill bit is reasonable in structure, the utilization ratio of the blades can be increased by more than 20 times, the use cost of the drill bit of the hole digger can be saved by more than 50%, and therefore the arc-shaped double-blade drill bit has great development, application and popularization value.