This research presents an implementation of Myanmar national grid model in Power System Analysis Toolbox (PSAT)¿free and open source software. It focuses on the application of newly developed hydro turbine and hydro overnor model with detailed dynamic power system models on Myanmar national grid because the power system network is largely supplied by hydro power. It demonstrates the classical small signal stability analysis of linearized grid model as well as the concept of network mode shapes to be elaborate.Transient stability assessments of benchmark system are carried out through nonlinear time domain simulation by applying both large and small disturbances and compared with the currently available PSAT models to demonstrate difference and necessity of accurate hydro turbine and governor model utilization. The fast Fourier transform (FFT) is used to convert the time domain signals into frequency domain for determining and checking particular frequencies of rotor speed signals. Moreover, a statistical t-test is performed to ensure the effective of proposed procedure to deal with dynamic problem of the power syetem.