The invention discloses a jig for drilling of a circular shaft. The jig for the drilling of the circular shaft comprises an upper jig and a lower jig which are used cooperatively, and is characterized in that two semicircular through grooves are respectively formed in portions of the upper jig and the lower jig, which are corresponding, a baffle is arranged on the same side of the semicircular through grooves, the baffle is inserted into the lower jig through clamp grooves in the lower jig, the number of the clamp grooves is more than one, the clamp grooves are formed in the lower jig in parallel mode, and vertical to the semicircular through grooves, another clamp groove is further formed in a portion of the upper jig, corresponding to the clamp grooves in the lower jig, two thread holes are respectively formed in edges of the upper jig and the lower jig in corresponding mode, and a bolt passes through the upper jig and the lower jig, and clamps the upper jig with the lower jig by cooperating with a nut. The jig for the drilling of the circular shaft is simple in structure and stable in clamping, achieves a fixing function in the radial direction of the circular shaft by using the upper jig cooperatively with the lower jig, achieves a fixing function for an axial device of the circular shaft through the baffle, and thereby clamps the circular shaft.