The goal of this study is to analyze the features of Korean eighth grade students’ achievement and its trend in life science domain in TIMSS 2011 and TIMSS 2015, and to explore its implications for Korean science curriculum and teaching & learning. With 6 science teachers and 3 science educators, we analyzed the features of Korean eighth grade students’ achievement in life science by test-curriculum matching analysis. We also compared students’ achievement trend among the 15 top-performing countries in TIMSS 2015. According to the results, compared with TIMSS 2011 Korean students’ performance decreased by 7 points in life science in TIMSS 2015, which caused the decrease of the Korean students’ overall science achievement in TIMSS 2015. According to the trend analysis of test topics with released items for life science domain in TIMSS 2015, Korean students’ percentage for correct answers have dropped in topics such as Heredity and evolution since these topics are covered in the ninth grade in the 2009 revised curriculum. For science cognitive domains, Korean students demonstrated relative weaknesses in ‘applying scientific knowledge’ domain in TIMSS 2015. Based on the trend analysis of students’ achievement and response for test topics and released items, we suggested implications for middle school bio-science curriculum development, and ways to improve science teaching and learning for students’ better inquiry skills and real-world application of science knowledge.