This study aims to determine the learning difficulties of high school students in the high school science class in Sibolga in the digestive system material, to know the students' learning difficulties in the digestive system material, to know internal factors and external factors that affect students' learning difficulties in the digestive system material, to know the level of thinking ability critical students. This research is a qualitative descriptive research that is describing and explaining data based on the existence of reality in the field. This research is also called non-experimental research because in this study, researchers did not control and manipulate the research variables. The results showed that the learning outcomes of high school students throughout Sibolga City in human digestive system material were in the low category. Students in SHigh School in Sibolga City have learning difficulties. The lowest indicator is in teacher quality indicators with an average of 54.5% with moderate criteria.