The development of classical mechanics to quantum mechanics not only represents the progress of natural science, but also has a profound influence in philosophy and social sciences, at the same time it changes people’s weltanschauung, and makes peoples’ understanding of causality experienced from determinism transition to the non?-determinism. With the tendency of non?-determinism in philosophy field, it has also appeared in the field of law especially in personal tort law, and it has found a specific approach in theory and practice: the doctrine of chance losing in the field of medical tort.