The effect of phosphorus slag powder on the mechanical property and micro-property of raw material phosphogypsum was studied.The mechanical property was studied by bending and compression testing machine.The micro morphology was studied by SEM.Results showed that addition of FDN were 1.5‰.The additions of modified phosphorus slag powder was at 10%~15%.The flexural strength and compressive strength of phosphogypsum-based products were above 7.0 MPa and 15.0 MPa respectively.It was about 2 times than the blank sample.The micro morphologies of phosphogypsums before and af-ter hydration were analyzed by SEM.Results showed that the micro morphology of phosphogypsum-based mortar grew from flake or strip to short column or hollow tubular structure after adding phosphogypsum modified material,which greatly improved the performance index of phosphogypsum-based mortar material and provided theoretical and technical support for the production of gypsum mortar with phosphogypsum.