Based on the assessment method of environmental vulnerability constructed by SOPAC and UNEP, this paper constructed an indicator system from three sub-themes including hazard, resistance, and damage to assess the eco-environmental vulnerability of Hainan Island. The results showed that Hainan Island was suffering a middling level eco-environmental hazard, and the main hazards came from some intensive human activities such as intensive agriculture, mass tourism, mining, and a mass of solid wastes thrown by islanders and tourists. Some geographical characters such as larger land area, larger altitude range, integrated geographical form, and abundant habitat types endowed Hainan Island higher resistance to environmental hazards. However, disturbed by historical accumulative artificial and natural hazards, the Island ecosystem had showed serious ecological damage, such as soil degradation and biodiversity loss. Comprehensively considered hazard, resistance, damage, and degradation, the comprehensive environmental vulnerability of the Island was at a middling level. Some indicators showed lower vulnerability, but some showed higher vulnerability.