The invention discloses a device for performing reduction treatment on drilling waste water by using diesel exhaust and a treatment method thereof, and belongs to a device and a method for treating the drilling waste water. The device comprises a rotary evaporator (1) and a heat exchange muffler (3). In the unit and the method, the exhaust of a drilling diesel is taken as a heat source without additional fuel supply, so the diesel exhaust is reasonably used, and the cost is low. Simultaneously, vapour evaporated from the drilling waste water can be recovered in a form of distilled water through the unit for additional use; and the drilling waste water after the reduction and concentration treatment is carried away to reduce the pollution to the environment. The device has the advantages of reduction treatment for the drilling waste water, the recovery of the distilled water, the utilization of the exhaust of the drilling diesel reasonably and thoroughly and the use of the rotary evaporator, simple treatment process flow, high efficiency, simple unit structure, wide application range and suitability for various drilling and exploration places.