The invention discloses a flow demand-based sawtoothed irrigation device reversal design method. The method comprises the following steps: sequentially determining the size of sectional area A of a sawtoothed flow channel according to the flow demand Q0 of the irrigation device and according to related formulas; after initially selecting the depth D of the flow channel, determining the width value W of the flow channel according to related formulas; after initially selecting the sawtooth angle theta, determining the sawtooth spacing B according to related formulas; initially selecting the sawtooth height; calculating the initial designed irrigation device flow Q1 on the basis of sawtoothed flow channel structural parameters: flow channel depth, sawtooth angle, sawtooth spacing and sawtooth height, which are selected, calculated and determined within the optimal range; calculating the deviation qv of the Q0 and the Q1, and affirming the size of each determined flow channel structural parameter of the sawtoothed irrigation device when qv is less than 5 percent; establishing an irrigation device internal structure geometric model by virtue of CAD drawing software, and designing the sawtoothed irrigation device which meets the flow demand Q0 under normal pressure or low pressure.