Abstract: The Zhundong mining area in Xinjiang province is abundant in coal resources, which are a great option for power plants due to its numerous benefits, including extremely low ash content, high calorific value, low flammability, and low sulfur content. Nevertheless, direct burning of high-alkali coal would cause significant fouling and slagging phenomena in boilers, affecting the safety and efficiency of boiler. In previous research, some mature models for forecasting the behavior of ash deposition have been developed. A summary of the creation, deposition, growth process, and sticking criteria of ash particles in high alkali coal-fired boilers during numerical simulation is proposed. The principles, benefits, and drawbacks of various ash deposition models were illustrated in this work. This serves as the foundation for a review of the numerical simulation of fouling and slagging in high alkali coal-fired boilers, including the heating surface, convection tube bundle, superheater and reheater surface, and burner area. The differences of fouling and slagging between high alkali coal-fired boiler and ordinary coal-fired boiler are discussed. The high content of Na and organic combined elements in high alkali coal are easy to gasify during combustion, which makes it easier to form fine particles. Condensation deposition is also the main mechanism leading to serious fouling and slagging in the high alkali coal-fired boilers. The phase transformation of submicron particles in high alkali coal ash, heterogeneous condensation of gaseous condensation of gaseous alkali and alkaline earth metals (AAEMs) compounds, and the coagulation of ultrafine particles promote the growth of deposited layers in high alkali coal-fired boilers. The high content of AAEMs compounds greatly enhances the ability of molten ash to capture particles. Meanwhile, the development direction of scientific research on high alkali coal-fired boilers is prospected. In order to better predict the ash deposition process of high-alkali coal, a more complex and comprehensive ash deposition model that takes into account the generation, impact, adhesion, rebound, erosion, and deposition morphology prediction of ash particles is required.