Aluminum (Al) toxicity is one of the most important limitations to agricultural production worldwide. The overall response of plants to Al stress has been documented, but the contribution of protein phosphorylation to Al detoxicity and tolerance in plants is unclear. Using a combination of tandem mass tag (TMT) labelling, immobilized metal affinity chromatography (IMAC) enrichment and liquid chromatography-mass spectrometry /mass spectrometry (LC-MS/MS), Al-induced phosphoproteomic changes in roots of Tamba black soybean (TBS) was investigated in this study. After AlCl3 treatment, 314 proteins harbouring 420 phosphosites, were significantly changed (fold change > 1.2 or < 0.83, p < 0.05) with 151 up-regulated, 157 down-regulated and 6 up/down-regulated. Enrichment and protein interaction analyses revealed that differentially phosphorylated proteins (DPPs) under Al treatment was mainly related to G-mediated signaling, Ca2+, transcription, translation, transporters and carbohydrate metabolism, roughly clustered for one of associated with inhibition to root growth, and another of citric acid production for resistance to Al detoxicity, which was facilitated by Al3+ through modifying phosphorylation of proteins responsible for carbohydrate metabolism. The results provide novel insights into the molecular mechanisms of TBS post-translational modifications in response to Al stress.