Phosphorus (P) speciation in agricultural soils determines its transformation, transport as well as fate. A comprehensive and accurate assessment of phyto-availability and environmental risk of soil P, particularly in the long term, cannot be achieved based only on routine soil tests for total P or available P. Therefore, it is essential to fully characterize and accurately understand the speciation of soil P for sustainable P management. Past research on characterization of soil P using the technique of traditional sequential fractionation could reveal information of operationally-defined P pools only, while researchers are currently able to identify soil P species at the molecular level with the aid of advanced spectroscopic tools, among which, solution P-31 nuclear magnetic resonance (P-NMR) and synchrotron-based X-ray absorption near-edge fine structure (XANES) spectroscopies are nowadays state-of-the-art techniques. These advanced techniques substantially facilitate our understanding of the various forms of organic, and inorganic P including P associated with Fe oxides, Al oxides and Ca minerals. Based on citation network analysis using Histcite software, this paper summarized key achievements of great significance during the development of the research on soil P characterization, reviewed development context of the research in this field over the last 30 years (from 1990 to 2019). It was found that the initial understanding of molecular P speciation, particular for organic P, in soils was mainly based on the technique of P-NMR, then more comprehensive understanding of soil P speciation at the molecular level was achieved once the technique was used in combination of synchrotron-based XANES and X-ray microprobe. Finally, this review presented a perspective on future trends of the application of multiple spectroscopic techniques in the research on soil P molecular speciation.