The occurrence, content and distribution characteristics of nitrogen and hydrogen impurities, which are widely present in natural diamonds, are of great significance for understanding the material cycle and for estimating the residence time of diamond in the deep mantle. Since the first diamond crystal was produced by the high temperature and high pressure (HPHT) method, researchers have obtained a large amount of data on diamonds synthesized at different pressures, temperatures (P- T), and media components. This paper systematically summarizes the occurrences and contents of nitrogen and hydrogen impurities in diamond crystals synthesized in the metal- carbon, carbonate- carbon, carbonate- silicate- carbon, sulfide- carbon, nitride- carbon, and nitride- sulfide systems. In addition, the influence of \[111\] and \[100\] orientations on the nitrogen and hydrogen content in diamonds is analyzed from the perspective of diamond crystal structure. We also discuss the effects of P- T conditions, components on the existence forms of nitrogen and hydrogen impurities in synthetic diamonds. It is also reviewed that the aggregation of Ib→IaA, IaA→IaB nitrogen defect in diamond lattice follows a secondary kinetic process of conversion. Combining the typical forms and contents of nitrogen and hydrogen impurities in different types of natural diamonds, this article can provide further research directions for the formation environment of natural diamonds from the perspective of nitrogen and hydrogen impurities.