Abstract: To study the pressure loss characteristics of the inter-stage bleed air structure and provide reference for the design of relevant structures in industrial gas turbines, a numerical study of bleed air structures in real industrial gas turbine multistage axial compressors is carried out by simulation, and the numerical domain including several main flow channels, bleed slot, bleed cavity, and off-take duct of the compressor. The results show that, under a small bleeding rate, the pressure loss due to the flow stagnation and turning at the bleed slot inlet accounts for more than 50% of the total pressure loss. Under a big bleeding rate, the pressure loss due to the flow mixing in the bleed cavity, and the flow separation at the inlet of the off-take duct account for more than 70% of the total pressure loss. The flow loss in different regions is affected by the bleed rate, the Reynolds number of the off-take ducts, and the hydraulic diameter of the bleed cavities. A zero-dimensional inter-stage bleed model can be trained by the neural network method for further performance evaluation.