Humic substances (HS) is the main part of natural organic matter (NOM), which have very complicated composition and structure, the reason called a kind of substances, is based on the common structural characteristics or the "distinctiveness" of their structure, formed in the humification process. But after nearly 200 years of exploration, the "distinctiveness" is still not clear. Faced with this dilemma, in recent years, some research results are deduced unreasonably, and there seems to question "distinctiveness" of HS. This relates to the foundation of HS chemistry and must be extensively studied and answered. In this paper, the existing researches, including the structural "distinctiveness" of humic substances，comparison of biological molecules monomer to the feature of the HS structure, HS formation with natural biological material based on biological diversity (evolution), formation mechanism of HS and formation sequence of humic acid (HA) and fulvic acid (FA), mineral clay catalyst for HS formation, modern techniques application such as heteronuclear single quantum coherence (HSQC), total correlation spectroscopy (TOCSY), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and synchrotron radiation soft near-edge X-ray adsorption fine-structure spectroscopy (NEXAFS) are waiting for carrying on review, and the direction for further HS research are put forward. The "distinctiveness" of HS will be studied in future in two ways: (1) Representative HS which come from different sources is compared with the recognized precursor monomers of biological molecules and bio-based (evolution) diversity of natural biomaterials. According to the differences, we can answer the question of the HS presence of "distinctiveness" and what is the "distinctiveness". (2) Choosing universal and controllable incubation conditions, the natural biological material is incubated by microbial inoculated incubation as the HS precursors. The differences of structural characteristics before and after incubation between products and precursors, the changes in the incubation process will be investigated by the same test method, to reply the HS "distinctiveness" is whether produced by the humification or not. The research idea should be that: No matter what the research results were, at least we could make the scientific mystery about whether the HS holding the "distinctiveness" or not and what was the "distinctiveness" seeming closer to the level of known. No matter which aspect was made breakthrough, it could provide the basic data for the HS biochemistry such as the formation, nature, chemical composition and structural characteristics, stability mechanism of HS and its relationship with the environment; It also could solve how to adjust the composition of HS through pre-setting the environmental conditions, which could provide the new theoretical basis for the regulation of soil fertility and carbon sequestration. In a word, based on the mention above, It could play a promoting role in the HS research and solve the scientific problems gradually associating with the HS from the different fields, such as the soil science, biogeochemistry, agronomy and environmental science.