Educational evaluation has become a popular trend since 1980's and has responded to social expectation and accountability of senior vocational education in Taiwan over the years.Competences of evaluating staff are much diversified and this study tries to build up a list of evaluation parameters, so as to explore the role-playing of evaluating committee. To achieve the set goal, this study proceeded the literature review, questionnaire survey via Delphi method of 30 experts to build the required list. To figure out problems gained from Delphi method, this study held 2 focus-group meetings and turned the conclusions into the questionnaire. 24 experts were asked to fill in the questionnaires.The conclusions obtained include:(a) Roles for evaluation parameters are designer, facilitator, educational trainer, inspector, investigator, diagnostician, consultant, mediator, advisory illustrator, information specialist.(b) Items of competence for external evaluating staff are divided into 3 categories: 1.systernatic inquiry-including 13 competence criterions 2.evaluation skills-including 11 competence criterions 3.evalution profession-including 6 competence criterions.(c) Evaluators of vocational high school have different roles and evaluation competences. Evaluation competences are much emphasized in the roles of diagnostician, consultant, and facilitator.