Background Techniques for petrographic analysis and tests of coals are critical to the accurate characterization of coals, oil, and gas, providing pivotal geological bases for coalfield exploration, formation condition investigation of coal deposits, clean and efficient coal utilization, and hydrocarbon resource evaluation. China's coal petrology commenced nearly a century ago, having progressively evolved into a key field serving the national energy strategy from the early-stage component identification and genetic investigation of coals. A standardization system suitable for the petrographic analysis and tests of coals with distinctive Chinese characteristics has been established. This system has found applications in industrial fields including coal exploration and mining, hydrocarbon exploration, and the coal chemical industry, providing theoretical and technical support for China's energy security and sustainable development. A systematic review of primary achievements in techniques for petrographic analysis and tests of coals and their industrial applications in China, as well as the exploration of the future prospects of these techniques, will help divert the attention of various industries to the development of coal petrology—a fundamental and interdisciplinary discipline.

Advances  Since the early 1980s, a relatively complete standardization system for petrographic analysis of coals has been established in China, incorporating the identification and classification of macroscopic to microscopic components, sample collection and preparation, and techniques for analysis and tests. This standardization system provides a fundamental guarantee for the rapid development and interdisciplinary applications of China's coal petrology. The techniques and instruments for petrographic analysis and tests of coals have evolved from manual to semi-automatic and then to fully automatic for partial techniques. Notably, the independently developed microphotometer that integrates a fiber optic spectrometer module, the technology for automatic petrographic detection of coals, and supporting reference materials have been exported abroad, marking a significant milestone in the development of techniques for petrographic analysis and tests of coals in China. The macroscopic components and macerals of coals play an irreplaceable role in the coal industry due to their unique physicochemical properties. In addition to the investigation of coal origin, both component types have contributed significantly to multiple fields, including the geology, exploration, and exploitation of coalbed methane, the industrial classification of coals, and techniques for the coal chemical industry.

Prospects  The development of techniques for petrographic analysis and tests of coals will drive the application of coal petrology, while intelligent petrographic detection and remote online petrographic detection services represent significant development directions of the techniques. The standardization system for coal petrology should be continuously optimized and improved with the automation and intelligentization of the petrographic detection of coals, aiming to more effectively serve the development and industrial application of China's coal petrology. Given the resource characteristics of special coal types, low-rank coals, and tectonically deformed coal in China, it is necessary to establish a corresponding petrographic classification system and evaluation methods for coals. This effort is expected to offer a critical basis for the clean and efficient utilization, hierarchical quality improvement, and targeted conversion of coal resources in China.