The invention provides a capacitor core cladding, a preparation method thereof, and a solid aluminum electrolytic capacitor. The preparation method of the capacitor core cladding provided by the invention is simple in operation, does not need to carry out high-temperature carbonization and saves energy. In addition, the capacitor obtained by the invention has the characteristics of high capacitance, low loss rate and low ESR value. According to the results of an embodiment, the capacitance of the capacitor obtained in this embodiment is 316 to 320 UF, which is much higher than the capacitance of 160 to 165 UF in a comparative embodiment; the loss rate is only 1.0 to 1.2%, much lower than 2.2 to 2.6% in the comparative embodiment; the ESR value is 10 to 11 milliohms, far lower than 16 to 18 milliohms in the comparative embodiment; and the 1-minute leakage current is 15 to 30UA.