Most of the systems used in day to day life are of fractional order. So analysis of fractional system is most important. But as it is difficult to design and realize a fractional order system in hardware by using available electrical parameters like resistance, capacitance etc; integral approximation of fractional plant is required. Several methods of approximation of fractional plant to integral order are discussed. Every method is analyzed in time and frequency domain. Also stability analysis is done using pole-zero realization.