The utility model provides a coal ash and calorific value measuring system. Two double-energy gamma ray transmission measuring devices are arranged in front of an inlet of coal combustion equipment and behind an outlet of the coal combustion equipment respectively, so that attenuation coefficients of coal and coal ash can be measured respectively; the coal ash and/or the calorific value are calculated by combining the attenuation coefficients of the coal and the coal ash; and therefore, the real-time measurement requirements can be met, the influence of high atomic number element content variation on coal ash and calorific value measurement is also eliminated, the coal ash measurement is not affected by variation in coal type, and the measurement accuracy is improved.