The invention discloses a method for separating and purifying oil sludge and sand. The method comprises the following steps of pre-treating, ultrasonic oil removing, microwave oil removing and purifying. The method has the advantages that the chemical agent demulsifying, ultrasonic treatment and microwave treatment are sequentially performed, and the recycling rate of oil is higher; by compositely applying ultrasonic treatment and flocculating, the oil removing effect is good; the waste liquid after oil draining can be recycled and reutilized by the low-temperature and normal-pressure catalytic wet type oxidizing treatment, and the water consumption amount is reduced.