It is an effective way to use the integrated pole piece structure in order to improve the output power of millimeter wave Folded Waveguide(FWG) Traveling Wave Tube(TWT). Based on the circular beam electron optical system, an integrated pole piece structure is designed for E-band folded waveguide TWT. In this paper, the cold characteristic parameters of slow wave structure are designed and simulated by using the Computer Simulation Technology(CST), and the integrated pole piece focusing system is designed. The magnetic field is simulated and verified by Operating Environment for Electromagnetic Research and Analysis(OPERA). The final Particle-In-Cell(PIC) simulation calculation results show that the output power of more than 1 kW can be obtained in the frequency band of 61-71 GHz. The integrated pole piece structure not only provides strong axial magnetic field, but also has the advantages of compact structure and good heat dissipation.