Abstract: The evaluation experiment of DRA is mainly conducted in indoor test loop. Indoor test loop has a small diameter and length, the flowrate of the oil in indoor test loops differs considerably from that in actual pipelines. In view of these shortages of indoor test loop, an outdoor test loop of 300 m-long with a diameter of 159 mm is designed and built, in which the flowrate of oil is more close to that in actual pipelines. Using high-pressure nitrogen as source power, the unit has high accuracy pressure transducers and high frequency pressure transducers along the test section, ultrasonic flow meter at the outlet of the test section, and high pressure tank and normal pressure tank. Because of the continuous variation in pressure, a transient model of the experiment process is established to calculate the change in flowrate and pressure, the range of Reynolds number as well as the experimental duration under different oil viscosity and various initial pressures.