Habitat fragmentation can reduce not only species abundance directly due to occupied patches being destroyed, but also the effective colonization rates indirectly. Moreover, habitat fragmentation can change the equilibrium among competitors. Previous studies to date consider habitat fragmentation to be the major cause of species loss. However, most analyses have been limited to the studies of consequences of habitat destruction. They do not reveal the driving mechanism. In this paper, we have studied the effects of habitat destruction and competition on species extinction in fragmented habitat. The results show that: the extinctions of superior competitors come from habitat destruction. However, the extinctions of inferior competitors decide by both habitat destruction and inter-competition under random destruction, and mainly by interspecific competition under edge destruction. The extinction time is much shorter when affected by habitat destruction and interspecific competition, while it is longer when affected by habitat destruction or interspecific competition. So, random destruction is more unfavorable for inferior competitors, and edge destruction is more unfavorable for superior competitors. Aggregated exploitation should be taken to decrease impacts on superior competitors, while random and disaggregate exploitation should be taken to decrease impacts on poor competitors.