[[abstract]]Abstract The present study investigates the effect of the cognitive semantic approach to English preposition instruction in comparison with that of the traditional approach. Besides, the learner difficulty with the various senses of prepositions in, on and at is analyzed. Moreover, the students’ responses to the preposition instruction in this study are also explored. Two classes of English grammar as an elective course in Chupei Senior High School (n = 70) participated in the study. The two classes were randomly assigned to be the control group and the experimental group. After the pretest that showed no significant difference between them, the two groups received the preposition instruction that adopted different approaches, i.e. the traditional approach for the control group and the cognitive semantic approach for the experimental group. Two posttests were then administered to determine and compare the effects of the two approaches as well as the students’ difficulties with preposition in, on and at. The students’ responses to the preposition instruction were also examined through a questionnaire. The results indicate that both the traditional approach and the cognitive semantic approach are effective in preposition instruction for the students. However, no significant difference is yielded between the effects of the two approaches. The results further show that abstract senses of prepositions in, on and at pose more difficulty than do concrete senses. Finally, an examination of the questionnaire reveals that the group adopting the traditional approach has more positive responses to the instructional materials than the group using the cognitive semantic approach.