The release of phosphorus (P) from anaerobic sediments becomes the dominant source of P loading with effective control of external P pollution. As a crucial component responsible for binding P, vivianite (Fe3(PO4)2·8H2O) in sediment inevitably impacts the P level and transformation. The release of P from vivianite mediated by sulphide was investigated using simulated overlying water-sediment and chemical reaction systems. The percentage of redox-stable P in the sediments increased with vivianite input in the overlying water-sediment system. Increasing P concentrations in both the overlying water and interstitial water occurred before day 10, accompanied by a decreasing percentage of redox-sensitive P in the sediments driven by sulphide. The continuous release of P from vivianite clarifies the influence of sulphide on promoting vivianite dissolution in a chemical reaction system with vivianite and sulphide solution. Additionally, Mössbauer spectrum and nanoscale secondary ion mass spectrometry (NanoSIMS) images based on the chemical reaction with 57Fe isotope labelling demonstrated the presence of initial vivianite, newly produced vivianite, and FeS2.