Abstract: Humic acid exists in nature widely,which is a kind of natural organic polymer compounds,and humic acid is abundant in the low rank coal such as lignite and weathering coal. In this paper,the resource reserve,regional distribution,species and properties of ore-humic acid was introducedin China. The traditional physical and chemical processing method of humic acid was compared with the microbiological method.Based on the research of microbial treatment of low rank coal in recent years,the microbial species(mainly actinomycetes,bacteria and fungi) and co-culture germs which can degrade low rank coal to produce humic acid were summarized. In addition,the extensive application of ore-humic acidwas described. As a kind of soil improver,humic acid can fix the heavy metal ions in the soil,absorb and promote the degradation of pesticides,polycyclic aromatic hydrocarbons and other organic matters,and reduce the enrichment and toxic effect of heavy metals in plants,and relieve the pollution of soil.As an organic biological fertilizer,humic acid also plays a role in agricultural production.It plays a great role in promoting crop growth,enhancing crop stress resistance,improving the quality of agricultural products,boosting the utilization rate of chemical fertilizer,increasing the structure of cultivated soil,and regulating the water,fertilizer,gas and heat conditions of the soil,promoting the root system development of crops,and increasing crop yield and achieving sustainable agricultural development.In the field of medicine and petroleum industry,ore-humic acid is also widely used. Natural humic acid has the functions of hemostasis,promoting blood circulation,antibacterial,antiviral,improving microcirculation,regulating endocrine,improving immunity,etc. Humic acid drilling fluid products are also gradually welcomed by petroleum enterprises because of their non-environmental pollution,resistances of high temperature and scale.Ore-humic acid has been applied in many kinds of production practices with good effect,but the basic products of humic acid are few,and the influence of source in different areas and treatment technology on the quality of products is quite different,so it is necessary to strengthen the comprehensive analysis of the processing technology of ore-humic acid,the physical and chemical characteristics of products,the effect on soil and biological effect and so on. The regional development and compound utilization of humic acid need to be vigorously promoted,especially medical application. The production of humic acid from low rank coal resources by microbial transformation has many advantagesthat the traditional physical and chemical treatment technology cannot compare,such as simple technology,low energy consumption,pollution-free and the like,but at the same time,there are also some problems for instance long growth cycle and low production efficiency. It is an important research direction to further research the mechanism and regulation way of humic acid produced by microbial action on low rank coal.