BACKGROUND Mixed reality (MR) is a hybrid system that projects virtual elements into reality. MR technology has the advantage of providing immersive learning using various real-world tools. However, studies on educational programs using MR are scarce. OBJECTIVE This study aimed to investigate the educational effects of and satisfaction with an MR-based trauma decision-making simulator. METHODS A total 40 of trainees self-selected to participate in this experiment. All participants participated in the MR trauma simulator for approximately 30 minutes and conducted voluntary learning without any external help. Declarative knowledge, measured using 20 multiple-choice questions, was assessed before and after MR trauma training. To confirm the educational effect, test scores before and after MR trauma training were compared using a paired t-test. Student satisfaction after training was measured using a ten-item questionnaire rated on a five-point Likert scale. RESULTS A pretest-posttest comparison yielded a significant increase in declarative knowledge. The percentage of correct answers to multiple choice questions increased (from a mean of 42.3, SD 12.4 to 54.8, SD 13) after the MR-based trauma assessment and treatment training (P < 0.001). Of the participants, 79.45% were satisfied with the overall experience of using the MR simulator. CONCLUSIONS This study demonstrated a meaningful educational effect of the MR-based trauma training system even after a short training time.