"Since the implementation of the 12-Year Basic Education Curricula in 2019, the competency-based assessment has become the focus of the teacher’s attention. Among them, professional and practical subject teachers in vocational high school are facing this additional requirement, the implementation of practical ability assessment. On the occasion of the full launch of the new guidelines, it is important to inquire whether the teachers are perceptually troubled by competency-based assessment. Thus, this study aims to survey professional and practical subject teachers for their opinions to the predicament of competency-based assessment, to verify the content and structure of the predicament, and to gather teachers’ coping strategies. This study was proceeded by means of a questionnaire investigation and focus group interview. 548 sample questionnaires from professional and practical subject teachers were collected. 12 teachers attend the focus group interview. The conclusions are as follows: 1. The predicament of professional and practical subject teachers can be induced into three factors: competency assessment, external resources, and contextual influences. 2. Although the level of predicament perception of competency-based assessment for professional and practical subject teachers is not high, the 'government's unclear policies of practicum subject learning assessment' based on contextual influences are most recognized. 3.Teachers' opinions on the items of the implementation of the competency-based assessment will be affected by whether they’re from public or private schools, whether they are certified teachers, and which professional subject group they are in. 4. Strategies for coping with the predicament of competency-based assessment starts from teachers’ self-improvement consciousness and action, with the hope that the government will set up a thorough implementation mechanism and examples of evaluation for different subjects before taking further steps."