The invention belongs to the technical field of drilling machines, and particularly relates to a deflection mechanism used for a drilling machine. The deflection mechanism comprises a base, a first sliding unit, an angle adjusting unit, a deflection unit and a drilling arm. The first sliding unit, the angle adjusting unit, the deflection unit and the drilling arm are all arranged on the upper portion of the base. The drilling arm is mounted above the deflection unit. The invention further relates to an application method of the deflection mechanism. The application method comprises the steps that firstly, the front-and-back position is adjusted; secondly, the vertical inclination angle is adjusted; thirdly, the deflection angle is adjusted; fourthly, the distance between a drill bit and the ground is adjusted; and fifthly, the drilling machine is made perpendicular to the construction ground. The deflection mechanism is simple in structure, convenient to operate, stable, reliable and long in service life, and when the drilling arm needs to work at a special place, the position of the drilling arm can be comprehensively adjusted.