Abstract: It is described the research on cast-in-place phosphogypsum for residential structure and the summary of construction technology according to the engineering practice． Phosphogypsum，phosphorus slag power，slaked lime and cement are mixed into dry material，and then water reducing agent，retarder and water are added to stir，and 27 cube specimens considering 9 kinds of mixture ratio are made to test the compressive strength and radioactive and setting time and moisture content etc． The compressive strength tests show that the standard values of compressive strength of cast-in-place phosphogypsum wall are between 2. 5 ～ 11. 0 MPa，the strength design values can be 0. 478 times of the standard values，and the phosphogypsum can be used for the filled walls of frame structure and the loadbearing walls of lower small bay residential houses． The volume of the retarder has an obvious effect on the compressive strength of cast-in-place phosphogypsum wall． The detection of the specimens show that the initial setting time and final setting time of cast-in-place phosphogypsum wall are respectively 45 min and 55 min，which can meet the requirements of on-site pouring process，and the results of radioactive test meet the technical requirements of the main material of building． The 5 d moisture content of wall was 2. 6%，which can reach its dry state．