The study aimed to investigate the effects of implementing the computer assisted problem-posing strategy on sixth-grade students’ English vocabulary learning achievement, retention effects, English learning motivation, and learning experiences. This study was a one-factor quasi-experimental design, lasting for 12 weeks. 64 sixth graders from an elementary school in Kaohsiung city were recruited and randomly assigned as the experimental group and the control group respectively. The former adopted the computer assisted problem-posing strategy, while the latter received the conventional English teaching. Research data were collected through the pre/post English Vocabulary Achievement Tests, an English Vocabulary Retention Test, the English Learning Motivation Scale, and Learning Experience Questionnaire. Data were analyzed quantitatively with descriptive statistics, independent-samples t-tests and dependent-samples t-tests. The results show that the experimental group performed significantly better than the control group in English Vocabulary Achievement test, English Vocabulary Retention test, and English Learning Motivation Scale. In addition, data collected from Learning Experience Questionnaire also indicate that the experimental group developed a very positive and supportive attitude toward the adoption of the computer assisted problem-posing strategy in their English learning.