Abstract: High sodium content in high-alkali coal leads to equipment fouling issues due to sodium volatilization when used as fuel for power plant boilers, affecting the normal operation of the equipment. Numerous studies have shown that fouling occurs because sodium, upon volatilization into the gas phase and then condenses on the low-temperature heating surfaces, adsorbing ash particles from the flue gas. However, there is limited research on the impact of chlorine content on the volatilization of sodium and potassium. The Factsage calculation method was used to study the volatilization of alkali metals in Wucaiwan coal at different chlorine contents. The results indicate that with an excess air coefficient is 1.2, sodium in Wucaiwan coal primarily volatilizes in the forms of NaCl and NaOH. As the Cl content increases, the NaCl content in the gas phase gradually increases with the rise in temperature. Chlorine primarily volatilizes as NaCl and HCl, and it completely volatilizes into the gas phase at 550 ℃. The HCl content decreases with increasing temperature and tends to remain constant. The NaCl content in the gas phase increases and then stabilizes with the rise in temperature, with the 800–1100 ℃ range being the significant increase temperature interval for NaCl. Below 990 ℃, the HCl content in the gas phase is higher than that of NaCl. As the temperature increases, HCl in the gas phase converts to NaCl. Potassium mainly volatilizes as KCl, and as the temperature increases, the volatilization of KCl increases and then decreases. At the same temperature, the volatilization ratio of alkali metals in Wucaiwan coal increases with the rise in Cl content, indicating that Cl can promote the volatilization of alkali metals in coal. Comparing the test results of sodium volatilization ratios at 600, 700, 815, and 920 ℃ with the calculated results, it is found that the test results are much higher than the calculated results at the same temperature, suggesting that there is a significant difference between the Factsage calculated Na volatilization ratios and actual test results.