Washback effect is emerged by language testing and carries significant contribution to the achievement of language learning. Students’ language learning strategies might be affected by positive or negative washback. Thus, this study aims to examine the washback effect of speaking test on students learning and what language learning strategies the students adopted before and after the test in a vocational school context. This study employed case study qualitative research design to examine the washback phenomenon in depth. Data were collected by classroom observation to capture the real event of the speaking test. After the classroom observation, semi-structure interviews are employed to obtain the deeper understanding about the washback and strategies they adopted in preparing for and after the test. The data were analysed using six phases thematic analysis. The data were checked by using triangulation. The results of the study came to two findings. First, the findings reveal that the speaking test produced mainly positive washback at the micro-level across affective, cognitive, and behavioural dimensions, while simultaneously generating negative washback characterised by students’ effort to anticipate teacher’s question and pass the test. Second, the findings also reveal that the student used a variety of language learning strategies, including memory, cognitive, metacognitive, social, affective, compensation, and technology-assisted strategies before and after the speaking test. The drawn conclusion from the research findings is the speaking test extends beyond the measurement of learning outcomes by generating complex and simultaneous positive and negative washback, while encouraging the development of strategic language learning behaviours that support students’ communicative competence in vocational EFL education.