To explore the possible paths for achieving intensity reduction targets and the feasibility of each route,based on the stochastic frontier analysis model of energy efficiency,the maximum likelihood method was used to estimate the average energy efficiency of 84 countries from 1971 to 2014. In view of this model,we comprehensively considered five factors: energy structure,economic structure,human capital,capital stock,and potential energy efficiency. Using forecast data on the factors from authoritative sources,we have modeled 96 scenarios on the effects of each single factor and their combinations,and systematically analyzed the results of carbon intensity reduction in China along each possible path,and the efforts required to achieve the reduction target. It is found: first,increasing the potential energy efficiency makes the greatest contribution to the target,which are unlikely to be achieved through adjusting any single one of the five factors; second,to hit its target,China needs to optimize its energy structure( the fossil fuel ratio must be lower than 80%,and its average growth rate must be decreased by 2. 2%),economic structure( the service sector GDP ratio must be higher than 60. 4%,while the growth rate of non-service sectors must be lowered by 2. 4%),human capital and capital stock( both of which must maintain stable growth),and potential energy efficiency( which needs 1% increase). Based on the above studies,the following policy recommendations are given: first,continuously improving energy efficiency through technological innovation and innovation in energy market mechanisms; second,accelerating the upgrading of the industrial structure and reducing the carbon emissions from production and living; third,continuously optimizing the national energy structure and promoting the reduction of source emissions; fourth,providing a stable and reasonable development space for human capital and capital stock,and providing essential support for carbon emission reduction.