Abstract: Background Oysters (Crassostrea spp.) are a major aquaculture species in China, valued for their high nutritional content, with a national production exceeding 7.25 million tonnes in 2024. However, industrial-scale processing is often hindered by the conventional manual shelling method, which is inefficient and labor-intensive. Ultra-high pressure (UHP) technology, a non-thermal process, has shown promise for shelling aquatic products. Nevertheless, comprehensive studies focusing on the efficacy, optimization, and mechanisms of UHP for oyster shelling are still lacking, limiting its industrial adoption. Objective This study aimed to systematically investigate the effects of UHP parameters—holding time, pressure, and holding temperature—on the shelling efficiency and sensory quality of oysters. The goal was to optimize the shelling process and establish a theoretical foundation for industrial implementation. Methods Single-factor experiments were conducted to evaluate the effects of different holding times, pressures, and holding temperatures on the shelling rate, shell-meat separation rate, meat yield, shell opening gap, and sensory quality. Orthogonal experiments were then employed to optimize and identify the best shelling parameters.Results The single-factor experiments demonstrated that increasing holding time, pressure, and holding temperature improved the shelling rate, shell-meat separation rate, and meat yield, while excessively high levels of these parameters adversely affected sensory quality. Analysis of the orthogonal experiments indicated that pressure had the greatest influence on the sensory score, followed by holding temperature and holding time. The optimal conditions were determined to be a 3-minute holding time, 250 MPa pressure, and 20 ℃ holding temperature. Under these conditions, the process achieved a 96.67% shelling rate, 92.22% shell-meat separation rate, 96.67% meat yield, a 6.91 mm shell opening gap, and a sensory score of 32.1. Conclusion UHP treatment proved to be an efficient method for shelling oysters while maintaining their sensory quality. The optimal process (3 min, 250 MPa, 20 ℃) demonstrates significant potential for industrial promotion and application.