To evaluate the micro-structural degradation characteristics and strength attenuation law of multi source solid waste solidified lake sediment under freeze-thaw cycle conditions, the macroscopic engineering characteristics of the solidified sediment material under freeze-thaw cycle conditions, such as unconfined compressive strength, volume deformation and permeability coefficient were observed through multiple repeated freeze-thaw cycle tests on samples of granulated blast furnace slag, desulfurization gypsum, and construction waste co solidified sediment. By combining micro testing methods such as X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy spectrum analysis, then the mineral composition, functional groups, surface morphology and elemental composition of solidified sediment materials during freeze-thaw cycles were systematically analyzed, revealing the micro mechanism of structural degradation of solidified sediment under freeze-thaw cycles. The results show that with the increase of freeze-thaw cycles, fibrous ettringite and columnar gypsum and other cementitious products fracture and overlapped with each other to form a network, and the internal pores increased. This may be the reason for the decrease in strength and increase in permeability coefficient of the solidified sediment. The obtained mechanical characteristics and degradation patterns of solidified sediment during freeze-thaw cycles can provide basic data for the application and promotion of this material in regions with significant freeze-thaw cycle characteristics such as northwest and northeast of China.