It is applicable in the industry such as electrical power, coal, commerce inspection, environment protection, metallurgy, papermaking, petrochemical, earth probe and the research institute or quality inspecting organization to test the content of air-dry basis moisture, ash, and volatile constituent in the coal. The instrument can also automatically calculate caloric value and the content of sulfur and hydrogen in the samples. Thermogravimetry, double furnace, automatically and continuously tests 19 samples a time. Moisture, ash (19 samples in 150 min), and volatile constituent (7 min a sample) can be tested separately in different furnaces.