Optical waveguides serve as fundamental components in integrated photonic systems, where minimizing propagation loss and enhancing refractive index modulation are critical for device performance. This study employs astigmatic beam shaping technology to fabricate low-loss optical waveguides in fused quartz (JGS1), systematically investigating the influence of laser parameters on waveguide quality and transmission characteristics. By optimizing laser processing conditions—including single-pulse energy (0.570.60 μJ), scanning speed (15 μm/s), and eight iterative scans—straight waveguides with a propagation loss of 0.231 dB/cm and coupling loss of 0.1 dB/facet were achieved. The fabricated waveguides exhibited high geometric symmetry in cross-sectional profiles and near-field mode circularity of 0.98.