Abstract: Electron optics system of W-band extended interaction klystron (EIK) which produces and transfers electron beam consists of Pierce electron gun and uniform permanent magnetic system. The Pierece electron gun is designed and optimized through Vaughan synthesis method and numerical simulation. What is more, the uniform permanent magnetic structure is developed according to transport character requirements of electron beam. Due to 3D program simulation of electron optics system for W-band EIK, parameters of gun are perveance of 0.21 P, current of more than 0.5 A, average waist radius of less than 0.3 mm and gunshot of more than 11 mm. In the permanent magnetic focusing system, magnetic field is about 0.33 T. Transmission distance of electron beam is more than 50 mm and transfer efficiency achieves 100%. The gun and focusing system are completely developed and product testing shows technical parameters satisfy the requirements. At present, the electron optics system for W-band EIK is in the state of installation and experiment.