The main purpose of this project was to improve the nurse's clinical judgement of an electrocardiogram (EKG). In the past, nurses less identify the patients' abnormal EKG at early stage. The accuracy rate of EKG interpretation was only 49.4%. The reasons for the low accuracy rate were lack of confidence and knowledge about EKG, insufficient update textbook, limited in-service education, and feedback after training. The strategies were developed including purchasing the latest edition of the textbook, developing clinical-based teaching material, designing self-learnt EKG simulation software, and establishing a feedback system. The accuracy rate of EKG interpretation improved to 88.9% in 2018 and at the follow-up period, accuracy rate increased to 90.7%. Moreover, nurses accurately determined the abnormal pulse rates increased from 76.7% to 91.7% and 97.1% relatively. We conclude that using self-learnt software with simulation design can enhance nurse's accuracy rate of EKG interpretation and improve patient safety.