The invention provides a reinforcement method, system and technology of oil-containing sludge ultrasonic demulsification. The reinforcement method includes the steps of filling oil-containing sludge with micro-nano bubbles, and conducting ultrasonic demulsification treatment on the oil-containing sludge filled with the micro-nano bubbles. The reinforcement system includes an demulsification pool,an ultrasonic amplitude-change pole capable of moving is arranged at the middle of the demulsification pool and is connected with an ultrasonic transducer, a first micro-nano bubble generator is arranged at the bottom of the demulsification pool, an oil-containing sludge inlet of the demulsification pool is formed in a side wall of the lower portion of the demulsification pool, a sludge outlet ofthe demulsification pool is formed in a side wall of the lower portion of the demulsification pool, and the side wall where the oil-containing sludge inlet is formed is opposite to the side wall wherethe sludge outlet is formed. According to the reinforcement method, system and technology of oil-containing sludge ultrasonic demulsification, a micro-nano bubble technology is utilized for assistingultrasonic waves in reinforcing demulsification effects of heavy and poor-quality oil-containing sludge; the method is continuous and efficient, the quantity of consumed chemical reagents during treatment is greatly reduced, and the treating efficiency of the heavy and poor-quality oil-containing sludge is improved.