The invention discloses a method for treating methanol wastewater produced during production of natural gas under synergistic effect of ultrasonic waves and ozone. The method is applied to treatment of wastewater of an oil and gas field. The method is characterized by comprising the following steps of: feeding the methanol wastewater into a rotating packed bed, and introducing ozone in a refluent way; feeding outlet wastewater into an ultrasonic wave reaction device; generating .OH and other free radicals with high oxidation capacity under the synergistic action of ultrasonic waves and ozone, and oxidizing methanol in the wastewater; and feeding into a middle circulation water channel, and further performing catalytic oxidation. The method has the advantages that a good effect of degrading methanol is achieved, and the rotary packed bed improves the utilization rate of ozone; the free radicals with high oxidation capacity can be produced by ultrasonic waves under cavitation action, and the oxidation capacity of the ozone is enhanced further at high temperature and under high pressure locally by the ultrasonic waves; the oxidation of methanol in the ozone is accelerated under the action of active carbon loaded copper oxide and ferric oxide; and a small amount of dilute acid is added into the methanol wastewater, so that the effect of degrading methanol is improved.