This paper constructs the evaluation index system of land ecological security based on PSR (pressure-state-response model) and applies entropy method and modified grey correlation analysis method to calculate the security index of the whole land ecology. This paper also conducts the evaluation on the land ecological security of Changsha City during the 12th Five-Year Plan. The result reveals that the land ecological security of Changsha City between 2011 and 2015 is in a relatively secure state. Overall, the land ecological security of Changsha City is presenting an increasing trend and inclines to a secure state; from the perspective of subsystem, the pressure, state and response system are all presenting a fluctuant rising trend and the fluctuating range is relatively great; forest coverage rate, innocuous treatment rate of household garbage, area of nature reserve and comprehensive utilization rate of industrial solid wastes are the main factors influencing the land ecological security of Changsha City.