Based on the method of the intergovernmental panel on the climate change (IPCC), the paper intends to propose a model for measuring the amount of CO_2 emissions in accordance with the consumption amount, the net calorific value and the emission factor of aviation fuel-oil, along witha method for measuring the CO_2 emission intensity in correspondence with the CO_2 emission per unit of ton-kilometer. So far as we do, there are generally three kinds of airlines in China which are categorized into the central airlines,local airlines, and private airlines. Due to the differences of the three typesof airlines in running scales, resources and operational modes, the paper haschosen Air China, China Southern Airlines, China Eastern Airlines, Hainan Airlines, Sichuan Airlines and Spring Airlines as our research goals. Air China, ChinaEastern Airlines and China Southern Airlines belong to the category of centralairlines, Hainan Airlines and Sichuan Airlines are to be put into the category of local airlines, but Spring Airlines belongs to the private ones. Back to the topic, the paper has worked out the CO_2 emissions and emission intensity of Chinese air transportation and typical airlines from 2005 to 2010 by using the related data from 2006-2011 statistics of China civil aviation, and, via the comparative analysis, concluding that, with the increase of CO_2 emissions of Chinese air transportation and typical airlines, the CO_2 emission intensity hasbasically decreased year by year. And, the CO_2 emission intensity of Spring Airlines, one of the private airlines, tends to be much lower than the Eastern Airlines, one of the central airlines, also to be lower than Hainan Airlines and other local airlines. In addition, the CO_2 emissions and emission intensity of Chinese air transportation during the 12nd five-year plan period are predicted. Thus, the paper believes that the average ton-kilometer fuel consumption and CO_2 emission intensity of Chinese air transportation will have been decreased by 3.92% as compared with the 11st five-year plan period. And, inthis paper, we have come up with some likely-to-be-effective measures to reducethe ton-kilometer unit fuel consumption and optimize the emission intensity of CO_2 such as by improving the guest rate and load factor.