Objective To explore the effects of Orem self-care theory on the initiative and core competence of psychiatric nurses. Methods A total of 100 in-service registered nurses in the clinical department of our hospital were selected and used self-control test on them. Then we evaluated and compared their initiative and core competence respectively at the begin and the end of one year′s Orem self-care theory practice in Psychiatric Ward. Results The initial score of initiative was (23. 43+2. 25) and the score of core competence was (131. 43 ± 7. 19) before the practice of Orem self-care theory. While the score of initiative was (30. 17 ± 2. 26), the score of core competence was (150. 80 ± 6. 73) after 1 year′s the practice of Orem self-care theory (P<0. 01). Conclusions Application of Orem self-care theory in Psychiatric Ward can enhance the work initiative and give full expression to the core competence of nurses.