Abstract: As a solid waste produced in the process of coal gasification, fine ash is difficult to recover effectively, resulting in environmental pollution and resource waste. In order to promote its resource utilization, coal gasification fine ash was used as raw material to prepare activated carbon for supercapacitors by pickling deashing and low-temperature KOH activation, with the effects of activation temperature on the physicochemical structure and electrochemical properties of activated carbon explored. The results showed that when the activation temperature increased from 450 ℃ to 650 ℃, the specific surface area of activated carbon increased from 798 m²/g to 2399 m²/g, the total pore volume increased from 0.78 cm³/g to 1.98 cm³/g, and the mesoporous/micropore ratio increased from 0.927 to 1.113. In the three-electrode test, the mass specific capacitance of activated carbon (DA−650) activated at 650 ℃ reached 178 F/g (1 A/g@6 M KOH). In the double electrode test, the capacitance retention rate of DA−650 symmetric supercapacitor is 125.23% after 150000 cycles of charge and discharge test. It is indicated that the activated carbon based on coal gasification fine ash is prepared by pickling deashing and low temperature KOH activation process, and its capacitance characteristics are improved, which provides a reference for the high value utilization of coal gasification fine ash.