<p>This work examined the ultrasonic hydrothermal synthesis of zeolites from municipal solid waste incineration fly ash (MSWI FA). An economical and reasonable ultrasonic-assisted hydrothermal method was proposed to treat the fly ash, while kaolin was used to replace the traditional silica-aluminum chemical reagents as additives. The factor which has a significant effect on the efficiency of zeolite synthesis was illustrate, include the time of ultrasonic, ultrasonic power, hydrothermal time and kaolin addition ratio, and the optimal conditions were determined through one-factor experiments. The outcomes showed that zeolite products may be produced by ultrasonic hydrothermal treatment with high crystallinity (48.22%). The products prepared under different conditions were applied to the adsorption of lead-containing wastewater, and the maximum removal rate was up to 68.6%, the adsorption capacity reached 174.45&#xa0;mg/g. In order to illustrate the process by which the hydrothermal products adsorb, the adsorption isotherms and kinetics were investigated, and it was found that Freundlich adsorption model could better reflect the adsorption characteristics of the adsorption procedure, process with a correlation coefficient of R2 = 0.9717. In contrast, the primary adsorption rate model is more consistent with the adsorption behavior. This suggests that the hydrothermal product is a potential cation adsorbent. In addition, this study evaluated the heavy metal leaching behavior of the synthesized product, and the outcomes demonstrated was little to no leaching of six heavy metals from the hydrothermal output. This study provides new methods for the simultaneous harmlessness and resource utilization of MSWI FA.</p> Graphical abstract <p></p>