Renewable energy resource on islands is rich, which is of unique potential dominance in electricity development. In Taiwan, Green Island power system is a small, isolated system with a load level of 4.39 MW at peak and 0.81 MW at the minimum. It has been mainly fed from diesel generators. This paper is to study the effect of generator outage events on the system transient stability in the Green Island under a high penetration of renewable energy integration. Simulation results reveal that the system stability would not be affected and even improved as long as the renewable energy generators do not trip offline when system contingence occurs. Moreover, addition of one extra generator unit could significantly reduce the drop of the system's transient frequency. The work can provide several important operational experience to isolated micro grids with high penetration of renewable energy.