Abstract: Biomasses such as corn straw, cow dung, and blue-green algae, which are rich in phosphorus, are referred to as phosphorus-rich biomasses. Due to their abundant reserves and potential environmental issues, their individual gasification or co-gasification with other feedstocks holds promise for resource utilization. Understanding the migration and transformation behavior of phosphorus components in phosphorus-rich biomass during high-temperature gasification is crucial. The study selects corn straw, cow dung, and blue-green algae uses the continuous extraction method proposed by the European Union to extract total phosphorus and four forms of phosphorus elements（organic phosphorus, inorganic phosphorus, non-apatite inorganic phosphorus, and apatite inorganic phosphorus）. The migration and transformation of phosphorus species in these three materials before and after gasification are quantitatively analyzed using inductively coupled plasma-optical emission spectrometry. Fourier transform infrared spectroscopy was used to detect changes in phosphate ions, silicon-oxygen bonds, and other inorganic compounds and functional group peaks in the phosphorus-rich biomass ash and gasification residues. By utilizing X-ray diffraction spectroscopy and FactSage thermodynamic simulations, the changes in the phases and phosphate minerals in the slag are investigated, revealing the interaction mechanisms between phosphorus and other elements. The results show that gasification helps the migration of phosphorus elements from phosphorus-rich biomass into the solid ash, where they exist in the form of inorganic phosphates. It also promotes the transformation of organic phosphorus or non-apatite inorganic phosphorus in phosphorus-rich biomass into the more bioavailable form of available phosphorus. Before gasification, the phosphorus fractions in corn straw were mainly in the forms of non-apatite inorganic phosphorus and organic phosphorus, while in cow dung, they were primarily in the forms of non-apatite inorganic phosphorus and apatite inorganic phosphorus. After gasification, the main phosphorus fraction in the gasification residues of corn straw and cow dung is apatite inorganic phosphorus, with the ratio of apatite inorganic phosphorus to total phosphorus m(AP)∶m(TP) reaching as high as 90%. In contrast, for blue-green algae, the m(AP)∶m(TP) ratio increased from 1.17% before gasification to 43.28% after gasification. Phosphorus can exist in the ash as alkali/alkaline earth-phosphate minerals such as potassium phosphate, calcium phosphate, and whitlockite, formed by combining with alkali and alkaline earth metals, leading to a higher content of apatite inorganic phosphorus. Gasification can promote the migration and transformation of phosphorus from phosphorus-rich biomass to the solid ash, providing theoretical support for the development of gasification-based technologies for the synergistic treatment of phosphorus-rich biomass.