This article summarized the latest progress of a sub-project, Carbon Emission of Cement Production in China, undertaken by Chinese Academy of Sciences. This project seeks to establish a domestic CO_2 emissions factor calculation system for China's cement production. The Chinese-specific CO_2 emissions factor of cement production will provide a benchmark to support China's international negotiation on climate change and a baseline for setting emission reduction target. Considering the diversities in different production lines, a sampling survey of cement production lines covering various production technologies and scales has been carried out since the second half of 2011. A two-stage stratified random sampling with unequal probability is devised to ensure the sampling precision. By the end of 2015, 22 provinces have been sampled and a CO_2 emission factor inventory database consisting of 359 cement production lines has been established. The emission factor of cement production can be divided as three components: raw material calcination emission, fuel combustion emission and indirect emission. At present, international organizations like Intergovernmental Panel on Climate Change (IPCC) and World Business Council for Sustainable Development (WDCSD) and a number of developed countries have promulgated a series of calculation methods for CO_2 emissions of cement production with a default emissions factor. To provide a CO_2 emissions factor inventory better reflects the de facto situation of Chinese cement production, a bottom-up integration from factory-level to national level is proposed. Bootstrap and Monte Carlo simulation are exploited to provide the confidence intervals of the CO_2 emission factors of different production stages. Since the Monte Carlo simulation requires parameter distribution of inputs, the probabilistic distribution function of CO_2 emission factors for each production stage is fitted by maximum likelihood estimation and bootstrap simulation. Combining the probabilistic distribution of various CO_2 emission factors, uncertainties for cement emission factors of different production technologies are simulated. The simulation results are as followings: (1) the 95% confidence interval for direct emission factor and integrated emission factor of new suspension preheater kilns are 773.63?915.01 kg CO_2/t clinker and 626.44?810.82 kg CO_2/t cement, respectively; (2) the 95% confidence interval for direct emission factor and integrated emission factor of shaft kilns are 733.00?1012.88 kg CO_2/t clinker and 534.01?728.45 kg CO_2/t cement, respectively; (3) the 95% confidence interval for direct emission factor and integrated emission factor of special cement are 517.07?1305.20 kg CO_2/t clinker and 558.09?1280.11 kg CO_2/t cement, respectively. The simulation result shows that the process CO_2 emission of unit clinker is overestimated for 1.4%?3.4% and the clinker/cement ratio is overestimated for 12%?32% comparing to IPCC or WBCSD default emission factors. Compared to previous studies, the discrepancies of fuel emission factor are at the range of -27.63%?+6.25%.