The invention relates to a synchronous reckoning method of utility boiler efficiency and coal heat value as well as ash content and moisture content, wherein air supply temperature, smoke exhaust temperature, smoke exhaust oxygen content, carbon content in fly ash, boiler-fed fuel content, boiler evaporation amount, assembly electric generating load, main steam pressure temperature, reheated steam inlet/outlet pressure temperature, water supply pressure temperature and flow rate, steam drum pressure, reheater temperature lowering water jet amount and steam extraction pressure temperature of each heater of high pressure cylinder are read through a plant-level supervisory information system (SIS) of a thermal power plant; and the parameters as the water temperature and drainage temperature of the inlet/outlets of different-level heaters of the high pressure cylinder are synchronously reckoned by hypothesizing the initial values of the coal heat value, the coal ash content and the coal moisture content, utilizing a boiler anti-balance heat efficiency model, a dry air amount required for theoretical combustion and actual smoke quality simplified calculating model, an actual smoke quality calculating model, an actual smoke volume calculating model, an actual smoke amount calculating model, a boiler positive-balance heat efficiency model and a boiler effective utilized heat model, and establishing prediction and rectification methods.