Abstract: Herein, we reportedthedevelopment of X-ray tube electron optical system. First, a Mo-tip field emission array cathode without grid electrodes was fabricated. At 3400 V, the emission current and current density were 1. 46 mA and 516. 4 mA/cm², respectively. Next, the X-ray tube electron optical system, comprising the emission array cathode, focusing electrode and anode, was modeled and simulated with software CST particle studio for design optimization. The simulated results show that novel Mo-tipfield emission array was a reliable electron source for the X-ray tube. For example, the optimized electron optical system has the electric field of 4. 7 V/μm (the onset field of 3 V/μm), cathode area of 10 mm × 2 mm, and total emission current of 10 mA. Finally, the X-ray emission was evaluated. Irradiating at 30°, the 1 mm × 1 mm emission electron beam generated an X-ray effective focal spot of 0. 58 mm × 1 mm, satisfying the requirements of X-ray tube.