The invention discloses a high-power heating system of liquid-state metal sodium and an adjusting method thereof. The system comprises multiple high-power heaters; the power of each heater is 4.2 MW;and multiple heating units are divided. Each heating unit comprises one electric heater, an inlet valve, an outlet valve and a bypass valve. All the heating units are serially connected; the final heating unit is connected with a reheater; and the reheater further adjusts the temperature of a sodium outlet. The electric heating system introduces argon protection to isolate reactions between air and other gas and liquid-state sodium; and meanwhile, stable pressure of the heaters is maintained in such operations as high-amplitude load shedding, load reduction and load increment. The whole heating system is adjusted by a three-step scheme of on-off, high-power rough adjustment and low-power fine adjustment; and automatic feedback adjustment is introduced, so that the temperature of the sodiumoutlet of the whole heating system can meet the requirements of experiment working conditions. The whole heating system is economical, high in efficiency, safe, reliable and high in operability.