In this experiment,phosphogypsum,slag and lime were used as the main raw materials to prepare the curing agent for engineering muck,and the effects of lime and phosphogypsum on the mechanical properties of the curing agent were studied,and the hydration products and curing mechanism were analyzed by scanning electron microscopy(SEM)and X-ray diffraction(XRD)microscopic measurements.The test results show that quicklime has a better excitation effect on slag than hydrated lime,and phosphogypsum is added to the slag-quicklime cementitious material system to prepare engineering muck curing agent,and its main hydration products are aluminite and C-S-H gel,and with the increase of phosphogypsum specific surface area and the decrease of content,the mechanical properties of curing agent are improved.