The purposes of this study are as below: first, to explore the current situations of cognitive coaching process and reflection competence for the elementary principals, and second, to explore the relationship between cognitive coaching and reflection competence. The research data are collected through questionnaire survey. The samples include 255 elementary principals in Taipei County and Taipei City. A total of 198 samples are valid and the rate of retrieve is 99%. These collected data are analyzed by descriptive statistic, Pearson's product-moment correlation, and AMOS. The main findings of this study are as follows: (1) The elementary principals' perceptions for cognitive coaching process are at the higher degree. (2) The elementary principals' reflection competence is at the higher degree. (3) There is a positive correlation between cognitive coaching process and reflection competence. (4) The cognitive coaching process has positive and significant effects on the principal's reflection competence. According to the findings of this study, this author proposes several suggestions for the implementation of cognitive coaching and principal's reflection, and for further studies respectively.