Objective To understand the situation of patient safety competency among vocational nursing students and its influencing factors. Methods An explanatory sequential mixed methods design was utilized. A questionnaire survey using a general information form, the Patient Safety Competency Nurse Evaluation Scale, the General Self-efficacy Scale, and the Metacognitive Ability Scale of College Students, was conducted on 494 vocational nursing students. Then semi-structured interviews with 12 vocational nursing students selected through purposive sampling were conducted. Results The total score for patient safety competency among vocational nursing students was （131.22±30.55） points. Multiple regression analysis indicated that the length of internship, experience in patient safety education and training, attitudes towards patient safety education and training, metacognitive abilities, and self-efficacy were the main factors influencing patient safety competency (all P＜0.05). The qualitative study extracted four themes:lack of confidence in patient safety competency, challenges in patient safety competency, clinical literacy, and activation of metacognition. Conclusion The patient safety competency of vocational nursing students is above average level. It is recommended that school leaders and teachers take corresponding measures based on the main influencing factors and the personalized needs of the students to improve the level of patient safety competency among nursing students.