The returning of crop residues to agricultural soils are of great significance to the development of Green Agriculture and soil fertility improvement. In China, there are various types of crop residues with high abundance. It is essential to characterize phosphorus (P) speciation in typical crop residues to predict the crop availability after returning them to the agricultural fields. To date, liquid-phase phosphorus-31 nuclear magnetic resonance (³¹P-NMR) spectroscopy is a state-of-the-art technique for characterizing P species at the molecular level. However, there were limited investigations on the characterization of P speciation in crop residuals by ³¹P-NMR spectroscopy. Moreover, spectral peaks of different P forms, generally assigned based on the published literature, were significantly affected by sample properties (i.e pH), which resulted in large uncertainty and limited P forms to be identified. Therefore, with spiking experiments, this study used ³¹P-NMR spectroscopy to characterize molecular P species in different parts (straw, chaff and seed) of the typical crops, including corn, wheat, rice, cotton, soybean and peanut. The results showed that the total P content in all investigated crop residues was seed > chaff > straw. NaOH-EDTA extractable P ranged from 73% to 139% of total P, with an average value of 105%. Based on the spiking experiments, inorganic P forms (orthophosphate, pyrophosphate, tripolyphosphate) and organic P forms (phytate, α and β-glycerophosphate, adenosine monophosphate) were detected in the investigated samples. Additionally, as one type of orthophosphate diesters, deoxyribonucleic acid was first detected in this study. In all investigated straw and chaff samples, the major P species were orthophosphates, comprising 49.3%~71.6% of the NaOH-EDTA extracted P, while P in the seeds was mainly phytate (48.5%~82.9%). With correction for diester degradation, orthophosphate diester (17.1%~33.5%) was more than orthophosphate monoester (9%~13.5%) in crop straw samples. In contrast, the orthophosphate monoester and orthophosphate diester percentages in chaff samples were 8.8%~23.2% and 8.8%~24.6% respectively, and orthophosphate monoester was the main component in seed samples (57.6%~82.9%). It showed that the investigated crop residues, especially straw, probably release orthophosphate and orthophosphate diesters as labile P forms for subsequent crop uptake after returning to the soil. These results provide a significant scientific basis for crop residue returning and P fertilization management in agricultural lands.