The invention discloses a clamping mechanism of a rocker arm drilling machine, comprising a stand column and a rocker arm, wherein the stand column comprises an inner column and an outer column sleeved outside the inner column; the lower ends of the outer column and the inner column are provided with mutually-engaged tapered surfaces; and the outer column is sleeved with the rocker arm through a large hole. The clamping mechanism is characterized by comprising a rocker arm clamping mechanism and a stand column clamping mechanism. The clamping mechanism of the rocker arm drilling machine has the advantages that the clamping is reliable; a self-locking function can be realized at any state and the clamping mechanism cannot be automatically released; the clamping mechanism is convenient to manufacture, has no special parts and special materials, and is convenient and direct to assemble, adjust and maintain; no oil leaks, and the problem of 'oil and electricity separation' and the layout difficulty are solved; the clamping mechanism is operated with low noises, and working noises of a high-pressure oil pump and impact sounds in clamping and loosening process are not generated; a plurality of labor-saving structures are adopted so that the energy consumption is the lowest and no oil materials are consumed; and therefore, the production cost is saved.