With the implementation of the 12-year basic education, putting competency-based instruction into practice has become a serious concern in education, which needs to be addressed without any delay. Through the instruction of the curriculum featuring English competency combined with investigations of articles on current social and life issues, students are to be cultivated to become active explorers, with empathy and tolerance for people and things in their surroundings. Additionally, the acuity of students’ awareness of the international trends in the world is to be strengthened; Further, through the nurturing of the practical curriculum, students are prompted to perceive the coherence between classroom learning content and life situations. Through cooperative group learning, students are to become lifelong learners with the ability to respect and care for the thoughts of others, accept others’ views, explore the reasons of various phenomena, delight in learning, appreciate the beauty of people and things in life, and innovate. Senior secondary education is the most crucial link in students' learning, which is imperative for cultivating their interest in learning and for inspiring their learning motivation. Thus, when faced with complicated, ever-changing situations in the future, their foundation to remain composed in face of dangers can be strengthened. Hence, this paper took the English teachers of a senior public high school as its research subjects. It adopted the qualitative research approach, using methods such as interviews and document analysis to detail the context in which the English teachers of the case school developed the curriculum featuring competency and relevant actions and influencing factors in their planning of the English competency-based curriculum. Furthermore, this paper also investigated difficulties faced by the English teachers, along with their solutions, in implementing competency-based instruction, portraying concrete practices in competency-based instruction of the English teachers of the case school. Based on the analysis and findings of the case study, the following research results are concluded: 1).The English teachers of the case senior high school created an English competency curriculum direction and view of change, which has established a new learning style for students. 2).The teachers would constantly adjust and revise the curriculum featuring English competency through its planning and implementation. 3).Through the exchanges in meetings with teacher professional learning community, the school would guide the teachers in teaching practices and solve the practical problems faced in teaching. 4).The teachers would consolidate the life value of students’ competency, strengthen their learning motivation, and enhance their self-regulated learning ability. 5).The challenging factor in developing the curriculum for the case school was the enhancement of the teachers’ professional growth.