The streak tubes are widely used in National Ignition Facility (NIF), Inertial Confinement Fusion (ICF), and streak tube imaging lidar (STIL) as radiation or imaging detectors. The spatial resolution and effective photocathode area of the streak tube are strongly dependent on its operating and geometry parameters (electron optical structure and applied voltage). Studies about this dependence do not cover the full range of the parameters. In this paper, 3-D models are developed in Computer Simulation Technology Particle Studio (CST-PS) to comprehensively calculate the spatial resolution for various parameters. Monte Carlo Sampling method (M-C method) and spatial modulation transfer function method (SMTF) are employed in our simulation. Simulated results of the optimized spatial resolution are validated by the experimental data. Finally, the radii of the photocathode (R-c) and phosphor screen (R-s) are optimized. Geometry parameters of R-c=60 mm and R-s=80 mm are proposed to optimize the streak tube performances. Simulation and experimental results show that the spatial resolution and effective photocathode area of this streak tube are expected to reach 16 lp/mm and 30 mm-length while the voltage between cathode and grid (U-cg) is 150 V.