Normalization of cyanobacteria outbreak in shallow lakes yield lots of salvaging cyanobacteria biomass, which dramatically modify phosphorus (P) cycle in water column and the sediments. Based on studies of SCWG reactions, it was expected to solve the dewatering treatment difficulty in engineering issues and realize potential energy use. By way of cyanobacteria biomass SCWG reactions, this paper clarified major existence forms and distribution law of rich phosphorus, evaluated the corresponding roles that reactions parameters and properties of biomass raw materials played in the products' distribution and morphological process. In addition to this, it discussed effects of alkali additions on phosphorus forms and distribution, with a view to providing potential approach for phosphorus stabilization in SCWG products.