“順著” and “沿著” are two prepositions about path of action. The minor semantic differences between them are difficult to master in Chinese learning. Based on the large-scale corpus, this article tries to compare and contrast the two words synchronically and dychronically from the semantic and pragmatical percetives. It also compare the schemata of their typical images. The preposition “順著” appeared before “沿著”，thus it was used more frequently than “沿著”. The meaning of “順著”as a verb was consistent with the meaning as a prepostion; On the contrary, “沿著”appeared later than 順著，mainly used as preposition. From the synchronic perspective, “沿著” has higher use frequency than “順著”，which is evident in scientific works and news writing. The prominent image of “順著” is the real displacement of objects, moving in a certain direction with the aid of external force. The prominent image of “沿著” highlights the process and concomitant of motion, usually in different directions, whether in a straight line or in zigzag motion. When describing the virtual movement, “順著” is less abstract than “沿著”, and the sentence with “沿著” often has a lot of metaphoric meanings.