A great tsunami had stroke the northern coast of Taiwan in 1867. The study area is focused on Gongliao District, New Taipei City. The assumed earthquake scenario originated from Yap Trench is used for Cornell University tsunami model (COMCOT model) which simulates the wave height and wave speed of the tsunami triggered by the earthquake. The wave heights of the northern coast of Taiwan are then used as boundary conditions for overland flow simulation. Risk due to tsunami is defined as hazard multiplying by vulnerability. The maximum water depth, the maximum water speed due to tsunami and rising rate of water surface level are used for production of tsunami hazard map. As for vulnerability, population and habitat environment are taken into account. After evaluating hazard and vulnerability, the high tsunami risk area can be delineated, and can take suitable measures to reduce loss of life and properties.