The invention relates to a precise workpiece cutting device which comprises a machine platform module, a fixture module, a tool module and a control module; the machine platform module comprises a machine platform and a sliding rack; the fixture module comprises a connecting plate, a first clamping block, a second clamping block and a clamping cylinder; the connecting plate is connected with the upper end of the sliding rack; the first clamping block is connected with the upper end of the connecting plate; a vertical plate is arranged on one side, far from the first clamping block, of the second clamping block; the vertical plate penetrates through the first clamping block through bolts and then is connected with the second clamping block; the clamping cylinder is located on the vertical plate; a knife trough block is arranged on one side of the first clamping block; the tool module comprises a speed-adjustable motor, a circular saw blade and a compressing block; and the control modulecomprises a controller and a touch control display screen. The precise workpiece cutting device can achieve precise cutting and automatic charging on special-shaped tubular raw materials, the labor intensity is lowered and the production efficiency is improved.