China Steel Corporation (CSC), established for more than thirty years, faces a problem of hundreds of middle level managers who will retire from the company in the near future, many successors are needed in the short term. Thus, how to quickly and effectively upgrade the managerment competency of new managers through various learning method becomes an important subject. This study takes CSC as a practical case and uses the Analytical Hierarchy Process (AHP) to analyze the connection between the manager core competencies and their enhancement methods .There are four core management competencies, including Planning& organization, Communications, Measurement & Evaluation and Executive Leadership, and there are four different learning methods also, including Job Experince ,Mentoring ,Classroom Lecturing,and Knowledge reading. A total of 24 employees in CSC were interviewed, including eight new (be a mentee), 8 senior managers (experienced persons) and 8 senior directors (be a mentor). It was proceeded by questionnaire supplemented with in-depth discussion.This study also takes the references from both domestic and international literature reviews. Hill (2007), professor of Harvard University, pointed out that there are five misconceptions of managing ability for a new manager,and he also emphasized the importance of an experienced manager¡¦s mentoring role. So, this study take the Mentoring learing method as the main topic to compare with the other enhancement methods. The study found that the Executive Leadership is the most important of four core management competencies in the case company CSC with a weighting 0.430. The Job experience and Mentoring are the most important of four enhancement methods with the weighting 0.357and 0.337. Moreover, The study result also indicates that the Mentoring is the best way to enhancement the competencies of the Executive Leadership. If the mentoring relationship can be set up at the very beginning stage when the new manager have promoted and be kept by one or two years, the learning effect will be more fruitful.