Abstract: A method for spinal drilling operation is disclosed. The method includes the steps of disposing a guiding element on a vertebra; mounting an auxiliary element on a locating part of the guiding element; mounting a k-pin on the auxiliary element; locating the k-pin and removing the auxiliary element from the locating part; mounting a cannular driller having a holding part and a drilling part through the k-pin; and rotating the holding part to drive the drilling part for a reaming process. A guiding assembly for spinal drilling operation is also disclosed. Accordingly, the spinal drilling process can be conducted easier and more precisely.