The invention belongs to the industrial water treatment field. An anaerobic treatment method for drilling wastewater comprises the following steps: (a) domesticating anaerobic degradation bacteria; (b) primary feeding, namely feeding 0.1%-0.5% of anaerobic degradation bacteria, 20% of anaerobic activated sludge and 20%-30% of biological stuffing into anaerobic treatment equipment according to the volume of the anaerobic treatment equipment; (c) biofilm formation treatment, namely introducing nitrogen or carbon dioxide into the anaerobic treatment equipment, introducing diluted drilling wastewater supernate into the anaerobic treatment equipment each day, and controlling the CODcr value of wastewater in the anaerobic treatment equipment to be 2000mg/L-3000mg/L until methane gas is generated; (d) complementary feeding; and (e) precipitating. By virtue of the anaerobic treatment method, the degradation effect of the drilling wastewater can be improved.