Abstract: Some important information of the induction motor which cannot be measured directly can be obtained by state reconstruction. However, the mathematical model of a full order observer is a four order differential equation, which is not easy to analysis and digitally implemented. Different discretization methods have different effects on the system performance. Four methods of full order observer digital realization are proposed based on the single footwork principle in numerical integration. These are first-order Euler method, second-order Trapezoidal method, and third-order and fourth-order Runge-Kutta methods. Validity, efficiency and precision of the four methods are shown with results of experiments on a 2.2 kW induction motor platform. 