This prospective randomized controlled trial evaluated the effectiveness of multi-scenario simulation teaching in improving practical competence among medical and nursing students during infectious disease training. A total of 121 students were randomly assigned to a simulation group (n = 60) or a traditional teaching group (n = 61). The simulation curriculum covered key clinical workflows, including triage, isolation, specimen collection, infection prevention, antimicrobial stewardship, and occupational exposure management. Primary outcomes were post-intervention Objective Structured Clinical Examination (OSCE) scores and critical action compliance rates. Secondary outcomes included clinical reasoning, teamwork and communication skills, learner satisfaction, self-efficacy, engagement, and cognitive load. Compared with the control group, the simulation group achieved significantly higher OSCE scores (mean difference 8.1; 95% CI, 5.4–10.9; Cohen's d = 1.14; P < 0.001) and critical action compliance rates (10.5% higher; 95% CI, 7.3–13.6; Cohen's d = 1.23; P < 0.001). The simulation group also demonstrated improved teamwork, greater satisfaction and self-efficacy, and lower cognitive load. These findings indicate that multi-scenario simulation teaching enhances practical competence, safety-critical performance, and learning experiences in infectious disease education.