Abstract: 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 0017 in 1995 to 0022 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.

Key words: pressure-state-response model, emergy analysis, urban ecological security, apple, long-term fertilization, yield, quality, soil fertility.