The influencing factors of the landslides were evaluated by comparing the occurrence of landslides in Lawnon River basin prior to and after the rainfall and earthquake events in recent 5 years (2005-2009). The landslide ratio in the study area was low (less than 4%) before 2007 and it significantly increased in the event of typhoon Morakot in 2009. The enormous accumulative rainfall is the major triggering factor. In addition, a major seismic activity in March 4 2008 is also vital to landslide occurrence. No evidential coseismic landslides were found in March 4 earthquake, 2008, however, the influence on slope stability has been observed from the apparent growth of landslide ratio in the four rainfall events followed by the quake. In addition, the existed landslide areas are more sensitive to landslide enlargement/development. The failure ratios of enlarged landslides is larger than those of new landslides, which indicates as a landslide occurs, it will be more easily to initiate subsequent failure nearby.