This study focused on the investigation of objects and contents of environment-related chapters which were contained in the biology textbooks of middle school in the 5th curriculum, and in the 6th curriculum. As a result of objects analysis, cognitive domain such as the knowledge and information categories were allocated more than affective domain as skill, value and attitude, and behavior and participation. Compared with the 5th curriculum, the average-pages of environment-related chapters in the 6th curriculum were decreased. Environment-related chapters in the 6th curriculum also dealt negligibly with the real environmental problems in our country. Therefore the importance of the environment-related chapters of biology textbooks in the 6th curriculum was relatively deceased compared with that in the 5th curriculum. In considering the actual low optional rate of environment subject in middle school, it was thought that the reinforcing effect of environmental education can be hardly expected. Rather, the status of environment subject will grow weaker and weaker. Thus, in order to avoid the deterioration effect of its status and solve its problems, it is necessary to up-grade environment subject as obligatory course or needs strong reinforcement of environmental education.