In order to ease the pressure on oil price, the downhole oil-water separation system has been adopted to preseparate the output production. However, both the gravity separator and the conventional hydrocyclone in this system have some restrictions, which hinder their widespread application. Therefore, it is necessary to innovate and improve the performance of the oil-water separation device. This paper presents a novel axial separator for oil-water separation based on analysis of droplet trajectory, and an experimental system was fabricated to test the separator. A high-speed camera was used to observe the droplet trajectories at the swirler, and the formation of the oil core was presented. Additionally, experimental investigation was carried out to evaluate the novel separation device in the water flow rate range of 3 to 7 m(3)/h with different inlet oil fractions. In addition, the effect of heavy phase outlet (HPO) pressure on separation efficiency was also studied. The results show that the separator exhibits good performance under the abovementioned experimental conditions. It was also found that the separation efficiency depends on the flow rate and the inlet oil fraction. Furthermore, increasing the HPO pressure is conducive to improve the separation performance.