How to reduce circulating current is extremely crucial to the design of stator windings. Many general transposition bars are used in AC machine to reduce circulating current losses, and incomplete transposition is widely used considering the level of reducing circulating current losses. However, the circulating current between strands with incomplete transposition will fluctuate to different extent when load current is changed. This study puts forward an improved incomplete transposition structure based on previous incomplete structure such that load current has little impact on circulating current, which could reduce circulating current losses in further. To validate the new structure, a 180 MW hydro-generator is taken as an example, and circulating current losses in strands are calculated by three-dimensional finite element method. The calculating results indicate that the improved incomplete transposition structure could reduce circulating current losses more effectively compared with previous structure.