Inertinite of coal rocks is a common micropetrological unit of coal and is transformed from fibrous tissue of woods. The inertinite not only identifies carbonization level of plants before forming coals, but also is an effective approach to reconstruct the paleoenvironment of peat and mire. In recent years, many European scientists have successfully used inertinite of coal rocks to calculate the wildfire temperature across the Triassic—Jurassic (T—J) boundary in the geologic history, recover the vegetation type and discover the paleoenvironment changes of peat and mire.