Abstract: The ash content of clean coal is a key quality indicator in the coal preparation production process of coking coal, achieving timely and accurate detection of ash content is the foundation for stabilizing product quality and improving economic benefits. In view of the existing problems of insufficient representativeness, lagged data and adjustment and others in the traditional manual sampling and chemical examination method, Wobei Coal Preparation Plant introduces two high-precision multi-element online coal quality analyzers based on Prompt Gamma Neutron Activation Analysis (PGNAA) technology, which are respectively used for online ash content monitoring of heavy medium clean coal and flotation clean coal. PGNAA technology utilizes a ²⁵²Cf neutron source to excite coal samples and generate characteristic gamma rays, achieves rapid quantitative analysis of ash content by analyzing the content of ash forming elements such as Si, Al, and Fe, etc. The on-site applications show that the analyzer has good adaptability under different coal types and particle size conditions, the absolute deviation of ash content detection in heavy medium clean coal is 0.12%, the absolute deviation of ash content detection in flotation clean coal is 0.13%, and the deviations of moisture and sulfur content are 0.31% and 0.03%, respectively, all of which meet the precision control requirements of enterprises. Supported by real-time detection data, a closed-loop control system for heavy medium ash content is constructed, and automatic adjustment of sorting density is achieved. After the system is put into use, the stability rate of process clean coal is improved from 55% to 85%, the stability rate of externally transported clean coal is improved from 88% to 98%, the average ash content of clean coal is improved from 10.70% to 10.82%, the clean coal yield is improved by 0.29 percentage points, and the annual economic benefits is increased by about 13.92 million yuan. This technology effectively improves the intelligent control level of coal preparation process and has good promotion and application value.