Tong fur is an important evidence for clinical pattern differentiation with great significance in objective measurement.This article systematically summarized the research progress of tong fur including color,thickness,dryness,greasy and putrid.The article proposed three problems to be further solved:Firstly,tongue fur classification criteria needs to be further unified; Secondly,the standard of tongue fur feature collection and reporting needs to be further established; Thirdly,the accuracy evaluation of tongue measurement instrument needs to become consistent.