Following the evaluation to green land abroad and drawing lessons from domestic study on data envelopment analysis (DEA), we did some evaluations to urban park green land which have not been studied much yet. Park green land is one part of urban green land system. Based on functions of fixing carbon and releasing oxygen, purifying environment, conditioning climate and detaining dust, we calculated the environmental benefit of park green land of ten districts in Guangzhou from 2001 to 2008. Then the input-output index system was built to evaluate the eco-efficiency of park green land in 2001—2008 by DEA. The land, labor and capital were taken as the input while the environment benefit was the output of park green land. The results showed that: firstly, influenced by the input of land and labor, generally, the environmental benefit of urban park green land presented an increasing trend but sustainable increasing ability was relatively weak; secondly, the input redundancy rate and insufficient rate of output in 2008 showed that the more input of fixed assets and financing of park maintenance caused low eco-efficiency in 2008; thirdly, the comprehensive efficiency, the technique efficiency and the scale efficiency were 1 in 2001, 2003 and 2004, which indicated the optimum efficiency. In 2002 and 2007, the comprehensive efficiency, the technique efficiency and the scale efficiency were between 0.895-1 which indicated the suboptimum efficiency. It showed non-efficiency in 2005, 2006 and 2008 in spite of over 0.8 in technique efficiency and scale efficiency because the comprehensive efficiency was below 0.8. Then it could be marked into two phases: stationary highly efficient phase in 2001—2004 and fluctuation non-efficient phase in 2005-2008, which meant the efficiency of urban park green land was low and unstable; fourthly, scale efficiency had a greater impact on environment benefit than technique efficiency influenced by fixed assets mainly, while scale efficiency was influenced by labor and land. Finally, we proposed some suggestions on enhancing the eco-efficiency of urban park green land in Guangzhou according to the findings. The government should increase input in urban park green land and labors to satisfy the need of environmental benefit outputs, and then control the proportion of input and output stably, especially the inputs. What's more, the supervision mechanisms of budget and the running of funds should be perfected.