The invention discloses a small diameter drill hole combined pressure relief arrangement method under an equivalent drilling area and relates to the field of surrounding rock control in mine and tunnel excavation processes. By converting a single large diameter drill hole into three small diameter drill holes, the areas of the small diameter drill hole areas are equal and the sum of the areas is consistent to the large diameter drill hole area, and the effective pressure relief range is improved obviously. By analyzing a strength and strain energy conversion rule of a test sample in differentarrangement modes of the drill holes and comparing and analyzing different combining modes of the small diameter drill holes and the range and pressure relief effect of a pressure relief area of the single large diameter drill hole, the optimum combining mode of the small diameter drill holes under the equivalent drilling area is determined. By researching the influence degree of proportion of thedrill hole diameters and the drill hole separation distances on the pressure relief effect of the drill holes in the triangular arrangement mode by means of a numerical simulation method, the optimumproportion of the drill hole diameters and the drill hole separation distances in the triangular arrangement mode of the drill holes is obtained. The pressure relief effect can be improved obviously,and the risk of hole collapse and hole blockage is reduced obviously.