Abstract: Based on the measurements in the Arctic Ocean, which were obtained for the first time using the Sound Velocity Profiler during the Chinese 9th Arctic Scientific Expedition, the structure of sound velocity profile, the sound velocity spring layer and homogeneous layer are analyzed. It reveals two distinct sound velocity profiles separated at 500 m depth in the surveyed area, where significant differences exist in the profiles shallower than 500 m. The measured minimum sound velocity is 1 426.5 m/s and the maximum is 1 512.5 m/s, with the minimum velocity exceeding the national standard range (1 430-l 550 m/s). Except for the observation station R20, the sound velocity spring layers were observed at all the other 30 observation stations. The number, depth, and thickness of the sound velocity homogeneous layers vary with observation stations. The types of the sound velocity profile are complicated and exceed the types defined in national standards. The formation causes of the sound velocity profile types are mainly affected by water temperature, salinity, and depth, in which the temperature change has the most significant impact on the sound velocity. The stable existance of surface warm water and deep Atlantic water as well as the unstable presence of residual AWW (Arctic Winter Water), ACW (Alaskan Coastal Water), sBSW (Bering Sea Summer Water), and wBSW (Bering Sea Winter Water) are the formation causes of new various types of vertical sound velocity distribution.