To promote the harmless disposal and resource utilization of fly ash, the leaching removal effects of four heavy metals (Cr, As, Cd, and Pb) in fly ash were studied through leaching with biodegradable organic acids: tartaric acid (TA), citric acid (CA), and oxalic acid (OA)—combined with orthogonal experiments and ecological risk assessment methods. The results show the following the average contents of Cr, As, Cd, and Pb in the fly ash exceed the Huainan soil environmental background values. They are higher by 0.38, 1.9, 14, and 1.90 times, respectively. Among the three organic acid leaching agents tested in the orthogonal experiment, CA is identified as the most effective. The highest removal rates of the four heavy metals are achieved under the conditions of 0.20 mol/L CA concentration and a solid-to-liquid ratio of 1∶15. The removal rates of the four heavy metals increase with higher leaching agent temperature, smaller fly ash particle size, and longer leaching time. Considering both leaching efficiency and cost for engineering practice, the optimal conditions are determined as follows: leaching agent temperature of 20~25 ℃, fly ash particle size of 75 μm (200 mesh), and leaching time of 120 min. After leaching with CA, the comprehensive potential ecological risk index (RI) for Cr, As, Cd, and Pb in the fly ash is below 150. The RI value is reduced by 45.23%, indicating a slight ecological risk level. In the risk assessment code (RAC), As is reduced from a very high risk to a high risk, and Cd is reduced from a medium risk to a low risk.It is concluded that CA leaching effectively removes heavy metals from fly ash and reduces its ecological risk. This provides a feasible technical approach for the harmless disposal of fly ash.