The oil-cooled flat-wire winding machines characterized with high electromagnetic loads and high power densities are widely used in for electric vehicle. However, high AC losses and large differences between the interlayer are inevitable when the motor operated in high-speed operation, posing serious challenges to reliable cooling of the motors. The transported winding with multi-segmented winding could significantly suppress the AC loss, but its end winding space structure is complex and might affect the cooling effect of winding. In this paper, the electrical machine with end transported winding is taken as the research object. The fluid-solid coupling model with oil and gas two-phase flow for the end transported winding is established, and the fluid distribution and local hot spot distribution are then analyzed. A new oil-injection structure is then proposed and are optimized with the Taguchi approach. The simulation result shows that the maximum temperature of the end winding is reduced by approximately 20 ℃ with the proposed oil-injection structure.