Based on the detailed examination of 10 large earthquakes with significant felt foreshocks in the Taiwan area, some interesting foreshock characteristics are obtained here. At first, most of foreshocks were found along the eastern coast of Taiwan, where is the convergent zone between the EUP and PSP and is generally considered as a strong heterogeneous crust. Besides, exactly similar to the foreshock characteristics in the western American (Abercrombie and Mori, 1996), the focal depths of 10 main shocks and their foreshocks were almost located at the upper crust, where the heterogeneity is stronger than those in the low crust and upper mantle. Focal depths of both foreshocks and main shocks in Table 1 were less than 18 km, except one foreshock located in the depth of 37.8 km. Both results strongly indicate foreshocks primarily occurred at the strongly heterogeneous upper crust. This characteristic observed in the convergent environment is similar to the foreshock pattern obtained in other plate boundaries such as transform faulting (Jones, 1984 and Abercrombie and Mori, 1996) and mid-ocean ridge (McGuire et al., 2005). In general, foreshocks (or micro-earthquakes) might be interpreted as the breaking of small patches of fault as they reach a critical stress, and thus leading to more foreshocks in regions with a higher degree small-scale heterogeneity zone (Abercrombie and Mori, 1996 and Lin, 2004). On the other hand, the critical stress on the different patches of fault in homogeneous region might be very close to each other, and thus there is no faulting until the tectonic stress overcomes the critical stress for all of patches at the same time. This means the main shock will occur without any significant foreshock in the homogeneous region.