Abstract: The ecological and environmental safety in the capital city is an issue always highly concerned by the government of China. In recent years, Beijing has greatly increased investment in forestry, and also attracted a wealthy of social funds to uplift the overall level of forestry and the forest ecosystem services. In order to improve the forestry input-output efficiency and to achieve the effective allocation of forestry resources and economies of scale, we selected six forestry input-output indexes, i.e., forestry investment in fixed assets, number of employees at the end of the year in forestry sectors, planting area, proportion of forestry industrial structure, output value of forestry industry and the rate of woody plant cover, and used DEA model which considers the return and scale (BC2-DEA model) to calculate the forestry input-output efficiency in Beijing from 1993 to 2013. The results show that the comprehensive efficiency of forestry input and output in Beijing is relatively high from 1993 to 2013. The average value of comprehensive efficiency is 0.966 in 21 years. As for the change of comprehensive efficiency of forestry input and output, the condition of forestry input-output in Beijing is good since 1993, and its efficiency is generally stable with small fluctuations. In the 21 years, 14 are in a state of DEA efficiency, and 7 in the state of DEA inefficiency. We also analyzed the main factors affecting the forestry input-output efficiency in Beijing, and point out that the change of the forestry investment in fixed assets is presently the main factor while the proportion of forestry industrial structure has little impact. In addition, factors like forestry investment management and production management also have an impact on the production efficiency. We propose that forestry investment in fixed assets in Beijing should keep stability in the future development and the industrial structure for forestry should be adjusted. Furthermore, the level of forestry investment and production management should be raised gradually and constantly in Beijing. Our study may bring important meanings to promote the coordinated development of forestry ecological economy, and improve the forestry input-output efficiency and forestry sustainable development in Beijing.