China has been facing a severe air pollution challenge in recent years. It is known that fine particulate matter is closely linked to haze. It is very important to have a good understanding of the formation mechanisms and sources of haze in China. This study provides long-term variation trends of meteorology and emissions during the past decades, reviews methodologies used in source apportionment of fine particulate matter based on published literature, and presents most recent source apportionment results from different cities in China, especially Beijing, the capital of China. Directions and key challenges in current source apportionment research are also discussed and suggestions are provided.