基于“压力-状态-响应(PSR)”模型，运用能值分析方法构建了城市生态安全评价体系和城市生态安全指数（EUESI），并评价了1995—2005年间唐山市生态安全水平的变化.结果表明：1995—2005年间，唐山市生态安全水平呈先升高后降低的趋势；基于能值分析的研究区城市生态安全指数由1995年的0.017增加到1996年的0.022后逐年降低，2003年进入不安全状态.基于能值分析的城市生态安全评价方法克服了传统评价体系的指标繁多、重复、单位不统一和可比性差等缺点，更加真实客观地反映了城市生态安全状态，为城市生态环境的管理和决策提供了科学依据.
Based on ‘pressure-state-response’ model and by using emergy analy
sis method, the urban ecological security assessment system and urban ecological
security index (EUESI) were constructed, and the variation of ecological securi
ty level of Tangshan City in 1995〖KG-*2〗-〖KG-*7〗2005 was evaluated. During t
his period, the ecological security level of the City increased first and decrea
sed then. The EUESI increased from 0017 in 1995 to 0022 in 1996, then droppe
d yearly, and became unsecure in 2003. The urban ecological security assessment
method based on emergy analysis overcame the disadvantages of conventional asses
sment system, e.g., numerous and repetitive indicators, non-uniform units, and
poor comparability, and reflected the urban ecological security state more objec
tively, being able to provide scientific basis for urban ecological environment
management and decision-making.