The invention discloses a cutting method applicable to a big board. The method comprises the following steps: 1) marking the board; 2) clamping one end of the board into a clamping mechanism, wherein the clamping mechanism comprises a base on which a vertical plate is vertically arranged; a chute is formed in the vertical plate, and an adjusting block is slidably arranged into the chute; a first lead screw is vertically arranged on the adjusting block; a clamping plate is arranged at the end part of the first lead screw; and the board is arranged between the clamping plate and the base; 3) adjusting the position of the base on a bracket to enable the marking position of the board to be under a cutting machine; 4) adjusting a limiting mechanism to arrange the board between the clamping mechanism and the limiting mechanism, wherein the limiting mechanism comprises a fixing column on which a second lead screw is vertically arranged, wherein a limiting plate is arranged at the end part of the second lead screw; and 5) sliding the cutting machine on a cross beam to cut the board. With the adoption of the method, the problem that an existing cutting system easily leads to inaccurate board cutting can be solved.