Abstract: To explore land ecological environment of resource-exhausted city in northwest region and its influencing factors, the author chose Baiyin City in Gansu Province as the case, and establishes an evaluation index system of land ecological security by applying the Pressure-State-Response (P-S-R) model and analytic hierarchy process (AHP) method. Combined with entropy method and Delphi method to determine the weight of each index, at the moment, the author estimated aggregated index of land ecological security to identify condition of land ecological security in Baiyin City. The results showed that: land ecological security index showed ‘W’ type trend, cut first, then increased, then reduced and increased. In 2004-2006, the aggregated index fell to 0.131562 from 0.574594, security level from the criticality safety drop to unsafe; in 2006-2010, aggregated index rose from 0.131562 to 0.131562, safety level from un-security rose to less security; from 2010 to 2011, aggregated index decreased from 0.378097 to 0.338470, security level had been in a less security; 2011-2012, aggregated index rose from 0.338470 to 0.416796, security level less safe from rising to criticality safety. In general, the ecological security of Baiyin City had experienced from good to bad and then gradually getting better trend, this paper provided useful information to improve the land ecological environment, therefore, it had important practical significance.