The invention relates to the technical field of solid waste recycling and materials, and relates to a preparation method of non-fired porous ceramsite with a high closed cell rate, which uses a foaming agent and an inorganic substance that promotes the decomposition of the foaming agent to realize step-by-step granulation and step-by-step manufacturing. Pores, promote rapid, uniform and thorough pore formation in the ceramsite core, and increase porosity; then, continue to granulate with the porous core and granulation mixture, and form a wrapping layer on the porous core, and complete the preparation and wrapping of the porous core in one step , to obtain ceramsite with a "porous core + wrapped shell" structure. Firstly, the raw materials can use mineral solid waste such as construction waste, tailings, fly ash, etc. to realize solid waste recycling; secondly, the porosity is high, and the thermal insulation performance is good; finally, the kernel and wrapping process are one-step during granulation Finished, the process is simplified, and the preparation cost is reduced.