The invention relates to an experimental device for generating cavitation bubbles on the basis of electric sparks and belongs to the field of basic subjects of water conservancy and hydropower projects. The experimental device comprises a transformer, a rectifying device, a capacitor, a high-speed camera and a computer system and also comprises a resistance bridge, air ball electrodes, a discharging water tank and tungsten-needle electrodes in the discharging water tank. For the transformer, a high-leakage-reactance testing transformer is adopted as a high-voltage generation device; a silicon-stack high-voltage rectifying device is adopted as the rectifying device; and the air ball electrodes, the discharging water tank and the tungsten-needle electrodes in the discharging water tank form a cavitation-bubble generation device. The experimental device has the advantages that the ball gaps among the air ball electrodes and the spacing among the tungsten-needle electrodes can be freely controlled, further the size of generated cavitation bubbles can be controlled and the testing needs can be better met; the whole experiment process is captured and recorded, and working operation with one-button type starting is realized; a circuit structure is optimized and is simple, and used materials are new; and the experimental device is small in size, low in cost and safe and convenient in operation.