Respirable dust generated during fully mechanized coal mining poses a serious threat to occupational health and safe production. To overcome the limitations of conventional high-pressure water spray systems, a novel gas–liquid two-phase spray dust suppression technology was developed and applied at the 22410 fully mechanized longwall face of Halagou Coal Mine in the Shendong mining area. Based on an analysis of dust generation characteristics and the physicochemical properties of respirable coal dust at major emission sources, the spray systems at the crusher transfer point, inter-shield region, and return airway were systematically optimized in terms of nozzle type, quantity, and spatial arrangement, with the original high-pressure spray devices replaced by gas–liquid two-phase spray units. Field experiments under actual mining conditions were conducted, and continuous multi-point measurements of respirable dust concentrations were performed. The results indicate that, compared with the original system, the respirable dust reduction efficiency at the crusher transfer point increased by 26.0%, while respirable dust concentrations in the inter-shield region were reduced to 21.0–22.1% of their original levels, and the maximum reduction in the return airway reached 69.2%. The gas–liquid two-phase spray system exhibited superior atomization performance and significantly enhanced dust capture efficiency, particularly in large-space and high-airflow mining environments. These findings demonstrate that the optimized gas–liquid two-phase spray system can effectively reduce respirable dust concentrations across fully mechanized longwall faces, thereby mitigating occupational health risks and improving mine safety, and provide a practical and reliable engineering solution for respirable dust control in modern coal mining operations.