For the purposes of simplifying the calculation task, adjusting production processes in time and solving the inconsistent requirements for carbon emissions, this paper investigates the calculation methods of carbon dioxide emissions from cement production, for example IPCC, WBCSD-CSI, MEE-CBMA, CNIS and BNU. Then a simplification and intuitive method is proposed. Based on the intuitive method, CO2 emission of 21 cement plants in China are calculated and analyzed, of which the error between the calculation results and those obtained by HJ 2519-2012 is less than 0.5%. About the carbon reduction technology in cement industry, there is limited reduction space that rely on energy efficiency improvements and clinker substitution. The technology of alternative fuels still needs to be further expanded. China has operated the first demonstration production line of CCUS technology at the Anhui Baimashan Conch cement plant with a capacity of 20,000 tons/year of industrial-grade liquid CO2 products and 30,000 tons/year of food-grade liquid CO2 products. Alternative raw material technology may be one developing direction to cut carbon emission; only 6.18% of steel slag was added to the raw meal at a 2500t/d production line, CO2 emission from process emissions were reduced by nearly 10%.