Using fly ash and desulfurization ash as the main raw materials, the fly ash -desulfurization ash unburned planting ceramsite is prepared by steam curing process. The effects of steam curing time, steam curing temperature, n(SiO₂)/n(Na₂O), desulfurization ash content and foaming agent content on the performance of the as prepared planting ceramsite were investigated. The phase composition, microscopic morphology and micro-domain composition of ceramsite were characterized by XRD, SEM and EDS. The results show that: when the steam curing time is 8h, the steam curing temperature is 80℃, n(SiO₂)/n(Na₂O)=5.0, the desulfurization ash content is 5%, and the foaming agent content is 0.75%, the planting ceramsite can be prepared with cylinder compressive strength of 3.56 MPa, while still maintaining the water absorption rate of 19.95% and the bulk density of 931kg/m³. The planting ceramsite prepared achieves a smooth surface, beautiful appearance, developed internal pore structure, strong water absorption capacity, and is rich in elements such as Si, Ca and S, which are suitable for plant growth.