The invention discloses a parallel type venturi tube cavitation device, which is composed of bolt holes, a flange plate, a fluid inlet, a contraction section, a fish mouth type dividing dike, a throat, an expansion section and a fluid outlet. The fish mouth type dividing dike divides the throat into two parts up and down, so that the water flow velocity of the upper and lower parts of the throat is faster, the throttling effect is good, and the cavitation phenomenon is obvious. A part between venturi tubes or between the venturi tube and a main pipeline is connected by the flange plate, so that the pipeline sealing effect is good, and the leakage probability is greatly reduced during a water flow oscillation process. The pipe diameter of the contraction section and the expansion section are gradually changed, so that energy loss caused by throttling in the venturi tube is reduced during a flow process. The parallel type venturi tube cavitation device has the advantages that the researched content is relatively wide and the applicability is relatively high.