The global food crisis has made food waste reduction an important area for research and practice. In China, food is frequently wasted in university canteens. Identifying the factors involved is critical for reducing waste and preserving resources and the environment. In contrast to previous studies of canteen food waste, which have mainly used quantitative research methods, this study adopted a qualitative approach to reveal the self-reported causes of food waste by students who eat at the canteens of a university in South China. The study identified material, economic, psychological, social, cultural, and health dimensions that influence food waste in university canteens. The results validate some previous findings and add novel factors not previously identified. This study argues that food waste is embedded in a complicated socio-cultural context, and hence it is difficult to take simple and direct management measures to reduce waste. Measures should be implemented to improve both the consumers' consciousness of frugality and ecological conservation, and the quality and palatability of the served food.