Based on the concept of urban ecological security( UES),the UES assessment indicator system of Ningbo is established according to PSR( pressure-state-response) model. UES assessment model is proposed from structural evolution of complex systems based on the maximum information entropy principle( MIEP),self-organizing feature map neural network( SOFM) algorithm and MATLAB mathematical software. The UES status of Ningbo shows an increasing trend from 2002 to 2011. In 2002—2009,Ningbo's UES is in critical secu...